Merge main into the desktop redesign branch

Four conflicts. Three were two people adding to the same spot, and one was a
real collision: main gave the connect bar a REMEMBER tick in the same pass that
this branch took the connect bar off the hosts screen.

REMEMBER is now in the drawer, beside the password box it qualifies. Nothing
about the feature changed — RemembersConnectPassword, its refusal to fire until
the remote has accepted the password, and the six tests over it are main's
untouched — only where it is drawn. The move improves it slightly and it is
worth saying why rather than claiming a merge was neutral: the bar had one row
and had to fit the box, the tick, the authentication note and CONNECT along it,
which is why the tick was a bare "REMEMBER" in tracked capitals. A column has
room to put it under the box as a sentence, where it reads as a property of the
password rather than as a fourth control in a row.

MainWindowViewModel: both sides added members after ShowTerminal — the desktop's
three fixed tabs here, the phone's connect menu on main. They do not interact,
so both are kept, each under its own heading.

TeamsScreen: main added the team's own RENAME, HAND OVER and ARCHIVE, a member's
LastActive, the role a new member arrives as, and the KEY HOLDERS list. This
branch had only bumped the file's font sizes a point. Resolved by taking main's
file whole and re-running the bump over it, so the new controls join the scale
rather than sitting a point below everything around them.

README: both sides described a different head's third pass in the same
paragraph. Both kept.

Two things checked rather than assumed, because this branch moved the furniture
the merged commits sit on. The chrome heights main's terminal work touched are
the phone's, not the desktop's — 44, 42 and 24 are unchanged, so the layout
harness's budget still describes the window. And main's keychain DELETE did not
reach VaultScreen.axaml, whose header this branch rearranged, so the five
buttons that overflowed at the larger type are still five.

2415 tests pass, up from 2369 by the 46 main brought.

docs/design-import-gaps.md

@@ -21,10 +21,17 @@ the chrome, hosts and terminals, file transfer, the vault, teams, and preference
 > over a view model that already existed, plus preferences. `ShellScreen` gained `More` and `Buckets`;
 > SFTP and S3 are one screen over one `TransfersViewModel`, differing only in which picker they offer.
 >
+> **A sixth is behind MORE that v2 never drew: TEAMS.** It is the reverse case — a shipped screen the
+> design had no slot for — and it is on the phone for a reason the design could not have anticipated,
+> because invitations did not exist when it was drawn. An invitation is claimed by *signing in*, and the
+> person being invited is at least as likely to be holding a phone as sitting at a desktop; a team the
+> server has just put somebody in, visible only on a head they may not have installed, is a membership
+> they cannot see. It runs over the same view model the desktop screen drives, like the other four.
+>
 > | v2 element | What ships instead |
 > | --- | --- |
 > | The **FORWARDING** screen: local/remote/dynamic rules, toggles, bytes transferred | **Nothing, said out loud.** `ISshConnection` offers `OpenShellAsync` and nothing else, so there is no tunnel for a rule to run through; `SyncEntityType.PortForward = 9` is still reserved and still unused. The MORE screen carries a paragraph naming the absence, for the reason the desktop keeps TEAMS in its rail. |
-> | `23 ms · fwd 5432` on the terminal's connection line | The account and endpoint actually dialled. There is no RTT measurement in SSH.NET and nothing forwards anything. |
+> | `23 ms · fwd 5432` on the terminal's connection line | ◆ **The line is gone, and what was real on it moved.** There was never an RTT to draw — SSH.NET measures none — and nothing forwards anything, so what shipped was the account and endpoint actually dialled. In v3 a connected phone draws one 35-pixel bar and then the terminal, so a second 36-pixel row naming the machine is exactly the chrome that surface exists to give back: the address is on the connecting card, where it is read before anything has answered, and the shell's own prompt says it afterwards. The two text-size buttons that shared the line are pinned at the end of the accessory row, outside its scroller, which is what the line was protecting them from. |
 > | `ED25519` badge and `SHA256:kQ9f…Zw2M` on every keychain card | `Detail`, which is what is genuinely known *about* an item. Unchanged from the first import: no algorithm field, no fingerprint, and computing either means parsing armour the type stores verbatim. |
 > | An `agent` chip on a key | Omitted. There is no agent of any kind — see the first import's Vault section. |
 > | Snippet cards footed with `edge-eu-1 · today 10:58 · exit 0` | The command and its badge. Nothing records where a snippet ran, when, or what it returned; the shell it is typed into never reports back. |
@@ -131,6 +138,13 @@ unused tables bought. See [Teams](#teams). What has *not* changed is the split u
 decides what it will serve, and only a client can decide who can read it — so "shared with" is two facts on
 this screen, not one.
 
+One table did have to be added, and what it shows is the limit of that reservation. An invitation names an
+**address**, and `team_membership.user_id` is not nullable and carries a foreign key, so somebody who has
+never signed in has nothing for that row to point at — which is why `MembershipStatus.Invited` has been
+reserved since the first migration and is still never written. `team_invitation` is its own table for that
+one reason. The schema was right about the shape of a team and had said nothing about the shape of joining
+one.
+
 **The client has no preferences store.** It writes exactly two files — `cache.db` and `device.key` — and the
 cache has six tables, none of them settings. Nothing on the design's TERMINAL preferences panel can be
 saved, and there is no frame on the terminal data plane that would carry a change to the renderer anyway.
@@ -320,9 +334,11 @@ and both editors. What follows is what the design drew around them.
 
 ## Teams
 
-**Built in M3.** The screen ships: a team list, a members table, the team's vaults, and the two buttons the
-whole design was really about — add a member, and share a vault key. What follows is what it still does not
-do, and one thing this document got wrong before it was built.
+**Built in M3.** The screen ships: a team list, a members table with a real last-active column, the
+invitations standing against addresses that have no account here yet, the team's vaults, and the two buttons
+the whole design was really about — add a member, and share a vault key. A team can also be renamed, handed
+to another member, and archived, the last only while it owns no vaults. What follows is what it still does
+not do, and one thing this document got wrong before it was built.
 
 **The correction.** The rows below used to describe a screen with nothing behind it, on the grounds that
 `VaultAccessService.ResolveAsync` denied every vault that was not the caller's own. That is now the one
@@ -331,6 +347,16 @@ place that changed, exactly as its remark predicted, and no migration was needed
 What the row did not anticipate is that the interesting half is not the endpoints at all. It is that
 **membership and readability are different things**, and the screen is arranged around saying so.
 
+**There are two ways into a team and they are not interchangeable.** Adding a member takes a *user id* the
+caller has already got from the directory, so that account must have signed in here at least once — and the
+ordering is deliberate rather than incidental, because whoever adds a member is usually about to wrap a
+vault key to the public key that lookup returned. Inviting takes an *address*, grants nothing readable, and
+cannot be a step towards sharing: there is no account, so there is no key to wrap to. Inviting an address
+that already belongs to a member of this team is refused and says so — that is a fact about a team the
+caller can already see. Inviting one that merely has an account somewhere on this deployment is **not**
+refused, because answering that would turn the endpoint into an oracle for which addresses have accounts,
+answerable by anybody willing to create a team first. It simply gets claimed sooner.
+
 | Design element | Layer | What ships |
 | --- | --- | --- |
 | The team itself | server | `POST/GET /api/v1/teams`, plus members, roles and team vaults. Ids are client-chosen, so a create whose response was lost is safe to repeat. |
@@ -338,17 +364,20 @@ What the row did not anticipate is that the interesting half is not the endpoint
 | Roles | contracts + server | `TeamMemberRole` on the wire, numerically pinned to `DodoSSH.Domain.TeamRole` by a test. Viewer reads, Member writes, Admin and Owner also share and administer. |
 | Members table | server | `TeamMemberSummary`, and a directory that resolves an exact email to a public key. |
 | Sharing an item | client | `VaultSession.ShareVaultAsync`: verify the recipient's key against the key log, wrap, sign, record. The server stores the wrap and the signature and can check neither. |
+| Pending invites, and withdrawing one | server | A `team_invitation` row per (team, address), listed beside the members it is about and withdrawable until it is taken up. It becomes a membership when an account with that address signs in — **and only if the access token asserts `email_verified`**, because membership is authorisation and an invitation anybody could take by naming somebody else's address is a way in. Fourteen days, because an address that is reassigned would otherwise carry a standing offer to whoever holds the job next. |
+| Ownership transfer | server | `POST /api/v1/teams/{id}/owner`, owner only. One transaction: the named member becomes owner and the outgoing owner becomes an admin. Not two role changes — ownership is sole, so promoting first leaves the team owned twice and demoting first leaves it owned by nobody. The outgoing owner is demoted rather than removed, because removing them would revoke their vault key grants and flag every team vault for rekey, which is a far larger act than the one being asked for. |
+| `LAST ACTIVE` | server | Real, and coarse on purpose. `UserAccount.LastSeenAtUtc` is now refreshed on ordinary authenticated requests, at most once per account per hour: writing it per request would put an UPDATE on the hot path of every authenticated call and start losing races on `user_account`'s own concurrency token. So the column answers "this week or not", which is the granularity the question is actually asked at, and is shown coarsely rather than to the minute. |
+| Renaming and archiving a team | server | `PUT` and `DELETE /api/v1/teams/{id}`. The slug is deliberately not renameable: it is unique only among *live* teams, so a rename could take a slug an archived team still holds and strand it. Archiving soft-deletes the team, every membership and every pending invitation in one transaction — and is refused outright while the team owns any vault. |
 
 | Design element | Layer | What it would take | What ships instead |
 | --- | --- | --- | --- |
 | `CONNECT-ONLY` role | — | Nothing that would be true. Connect is a user-interface hint, not a boundary: SSH terminates on the client, so a session needs the credential's plaintext on that machine. See ADR 0001. | Four roles, all of which are enforceable. `Connect` rides along with `Read` and is documented as a hint. |
-| `2FA ENFORCED` and the per-member 2FA column | server | No two-factor concept exists anywhere — the only hit in the whole worktree is an aside in `docs/crypto.md`. | Omitted. The member column carries what *is* known and matters: whether they have published a key a vault can be wrapped to. |
-| `LAST ACTIVE` | server | `UserAccount.LastSeenAtUtc` is written at just-in-time provisioning and at enrollment and never on an ordinary authenticated request, so the column cannot answer "last active". | Omitted. |
+| `2FA ENFORCED` and the per-member 2FA column | server | No two-factor concept exists anywhere — the only hit in the whole worktree is an aside in `docs/crypto.md`. | Omitted. The member columns carry what *is* known and matters: whether they have published a key a vault can be wrapped to, and when they were last here. |
 | Avatars | server | No picture is stored anywhere. | Omitted; the row shows a name and an address. |
-| Pending invites, resend, revoke | server | An invitation entity, a token with a lifetime, and an outbound mail path. `MembershipStatus.Invited` remains unwritten. | Adding a member resolves an address the caller types against the directory, so the account has to have signed in here once. The screen says that when the lookup finds nothing. |
+| The invitation mail, and **resend** | server | An outbound mail path: an SMTP configuration, a template, a bounce story and a deliverability problem, none of which this server has. | **Nothing is sent, and the interface says so.** An invitation is a standing instruction rather than a message — the next account to sign in with that address joins the team — so there is no token, no link, and nothing to resend. Telling somebody to sign in is done over a channel this server does not carry. A link nobody can deliver would be worse than no link. |
+| Archiving a team that owns vaults | — | Nothing that would be safe. A team vault resolves through membership, so archiving would take those vaults away from everybody holding a key, silently, including the caller — and nothing in this product deletes a vault, so there is no sequence of calls that turns the refusal into a success. | Refused, with `team-not-empty` and a count of the vaults in the way. A stated limit rather than a coming feature, for the reason the SFTP layer refuses a recursive delete: a refusal is visible and a quiet removal is not. |
 | `SSO · OIDC · okta.dodotech.dev` | server | Per-team SSO. Authentication is one global JWT scheme bound to one authority. | Omitted. |
 | A rekey after a membership change | client | Re-wrapping every item's data key under a fresh vault key, which only a client holding the current one can do. M5. | The vault is flagged `RekeyRequired` and the row says a rotation is owed. |
-| Ownership transfer | server | A confirmation flow and a rule for what happens to the outgoing owner. | The owner cannot be removed or demoted, with its own problem code rather than a bare 400. |
 
 > **The trap this document warned about is still a trap.** `GET /api/v1/meta` advertises
 > `features: ["teams"]` *unconditionally* (`MetaEndpoints.cs`). It was meaningless when nothing implemented
@@ -377,7 +406,7 @@ lists the rest as absent rather than omitting it silently.
 | `GENERAL` section | ui | There is no general setting to put in it. The theme is fixed by decision, and window size is not persisted. |
 | `KEYS & AGENT` section | client-ssh | **There is no agent, at all** — no own agent, no forwarding, no Pageant or OpenSSH-agent interop. |
 | `SYNC & VAULT` section | client-domain | Nothing here is adjustable. The auto-sync interval is a `private static readonly` with a remark arguing for its value. |
-| `SECURITY & SSO` section | server | The SSO half needs team endpoints; there is no policy for the screen to show. |
+| `SECURITY & SSO` section | server | Per-team SSO, which is a refusal rather than a pending endpoint: authentication is one global JWT scheme bound to one authority, so there is no per-team policy for this screen to show. |
 | `SHORTCUTS` section | ui | There is no keybinding infrastructure and no rebinding surface. |
 | Auto-lock after idle | client-session | An activity source, a decision about what counts as idle, and — the hard part — a policy for a shell mid-job. `LockAsync`'s own remark already argues that an unattended timeout which killed a running job would be worse than the exposure it removed. |
 | Require biometric to sign | crypto | Three separate falsehoods in one row. There is no signing service — the private key is decrypted and handed to SSH.NET whole, so there is no per-signature moment to interrupt; there are no connect-only keys; and per-use consent would need the key to live in the TPM, which is a different key hierarchy from the one in `docs/crypto.md`. |