Make Connections the place a connection is made, and put the keychain away

Four changes to the phone, and the last one needed the connect path taking
apart.

**The bottom bar is three entries.** The keychain moved onto the hub, which is
now SETTINGS with a gear rather than MORE with a hamburger. A bottom bar is for
the places a session moves between, and keys, credentials and tags are managed
occasionally and then left alone — which is the shape of everything already
behind that hub. With the keychain on it, "more" stopped being a description of
what is there. `ShellScreen.Vault` joining `IsMoreSurface` is the whole of the
change: the tab that lights, the header that stands down and the back gesture's
first case all read that one property, which is why the switch mirrors it by
construction rather than by a second list. The keychain screen grew the header
every hub screen has, because the shell's own is not above it any more and
without one there would be no back arrow and nothing saying what the list is.

The desktop keeps its Keychain rail entry. A rail with nine slots has room, so
this is the second thing the two heads arrange deliberately differently, after
the hub itself.

**Terminal became Connections**, and the word does more work than a rename
usually does — see below. The enum member stays `ShellSurface.Terminal`, for
the reason the tab was never called Vault: the surface is a terminal, and the
word a user reads is the product's.

**The + puts the software keyboard away.** It sits above a terminal somebody is
typing into, so the sheet it raises was arriving underneath a keyboard covering
the half of the screen the sheet is on — and worse, laid out into the strip
left above it, since the keyboard's inset shortens everything this head draws.
Avalonia cannot do this and it is worth knowing why: `TopLevel.InputPane`
reports the keyboard and offers nothing that closes one, because the framework's
model is that it belongs to whatever has focus — and this keyboard was raised by
the `WebView`'s own text input, by a native view Avalonia's focus manager never
owned. Clearing Avalonia's focus leaves it exactly where it is. So
`Platform/SoftKeyboard.cs` asks `InputMethodManager`, off the decor view's
window token, and every step of it is allowed to be absent.

**With nothing open, Connections is a connect screen rather than an empty
state.** A box taking `user@host` or `user@host:port`, a password, and the
machines most recently connected to underneath. The box is the only path in this
product to a machine the keychain has never heard of, which is a real case it
had no answer for: an address somebody was handed five minutes ago. A typed
password and nothing else — offering the keychain's keys would be a second
binding resolution beside `TryBuildAuthentication`, and the argument against a
second one is written there at length. Nothing typed is saved, and the screen
says so: a machine worth keeping belongs on HOSTS, where it can carry a key, a
group's defaults and a name.

The recents come out of the vault's own connection log rather than a list kept
in this process, so they survive a restart and arrive on a new phone with the
keychain. Deduplicated by address, because this is a list of places and not of
events, and capped at six so the box stays above the keyboard. Emptied when the
vault is — they are decrypted entries naming where somebody works, and a lock
that left them on screen would be a list still readable after every key that
decrypted it was zeroed. Tapping one leads to whichever of two things it is: a
keychain host goes to that host's connect bar, where its key, its password box
and its refusals already live, and an address goes back into the box, without
the password, whose absence is the point of that path rather than a gap in it.

**The connect path was shaped like `HostRowViewModel` all the way down.** The
log entry, the identification, the failure record and the retry all took a row.
They take a four-field `ConnectionTarget` now, so a connection to an address
shares the ladder of refusals, the host-key question and the tab's lifecycle
rather than growing a second copy of them. `ConnectionRecorder.Record` and
`Identify` have always taken a nullable host id, so the log could already hold a
connection with no item behind it.

One behavioural change falls out of that and it is the one to know about:
**trusting a host key now retries the attempt that raised the question** instead
of re-running whichever host is selected. That was correct while a selected host
was the only way to connect; with a manual target it would dial a different
machine, or refuse with "choose a host first" over a key the user has just
agreed to trust. The test selects a host first, so a regression cannot pass by
connecting to the wrong thing successfully.

`LogsViewModel.ReloadAsync` split so the connections half can be read alone.
Reading the keychain's activity for a screen that offers neither would double
the decryption on the list that was already the expensive one.

Twelve tests: the parse grammar as a theory over seven refusals, the dialled
request, the retry, and both branches of tapping a recent row. The recents rows
are built by hand rather than connected-and-closed — what those tests are about
is which branch a row takes, and driving it through the recorder's queue would
test the recorder, which `DodoSSH.Client.Session.Tests` already does. What needs
a device is phases 11.6 to 11.9 of `docs/manual-checks.md`.

docs/manual-checks.md

@@ -952,3 +952,54 @@ visibly disabled rather than silently inert.
 
 **Failure means:** they have been folded into the scrolling row — which is the arrangement the connection
 line existed to avoid, and the reason it could be removed at all.
+
+### 11.6 The keyboard goes away with the connect menu
+
+With a shell open, tap into the terminal so the software keyboard comes up, then press `+`.
+
+**Pass:** the keyboard drops and the sheet sits on the bottom of the full screen, all four of its rows
+reachable. Repeat on Android 14 or earlier and on 15 or later if you have both — the keyboard shortens this
+head's interface by a different mechanism on each, and a sheet laid out into the strip left above a
+keyboard is the failure this exists to catch.
+
+**Failure means:** `SoftKeyboard.Hide` found no activity, no input-method manager, or the wrong window
+token. Note that Avalonia cannot do this for us — `TopLevel.InputPane` reports the keyboard and cannot close
+one, and the keyboard here belongs to the `WebView`, so clearing Avalonia's focus is not a fallback.
+
+### 11.7 Connections, with nothing open
+
+Close every tab, then press Connections in the bottom bar.
+
+**Pass:** a box reading `user@host or user@host:port`, a password box under it, CONNECT, and — if this
+keychain has ever connected to anything — a RECENT list underneath. The whole thing scrolls with the
+keyboard up, and the password box shows dots with **no suggestion strip** above the keyboard.
+
+Type a machine you can reach and press CONNECT: a tab appears in the bar and the shell opens. Type
+something malformed — no `user@`, or `:70000` — and the refusal appears under the boxes, in the warning
+colour, with no tab and nothing dialled.
+
+**Failure means:** for the suggestion strip, the box lost `Classes="secret"` — see 10.1, and it is the same
+seriousness here, since this password is typed rather than stored and so is typed often.
+
+### 11.8 A recent machine leads to the right place
+
+With at least one keychain host and one machine connected to by hand in the log, open Connections with
+nothing running.
+
+**Pass:** tapping the keychain one lands on HOSTS with that host selected and its connect bar up. Tapping
+the hand-typed one puts its address back in the box on this screen and leaves the password box **empty**.
+Neither one dials anything on its own.
+
+**Failure means:** if the hand-typed one navigates to HOSTS, the log entry is carrying a host id it should
+not have. If the password came back, something is storing it — it never was.
+
+### 11.9 Settings holds the keychain, and back walks out of it
+
+From HOSTS: Settings, then Keychain.
+
+**Pass:** the bottom bar has three entries and the Settings one stays lit while the keychain is showing.
+The keychain draws its own header with a back arrow — the vault name and sync light are not above it. Back,
+by gesture or by the arrow, returns to Settings and not to HOSTS; a second back returns to HOSTS.
+
+**Failure means:** `ShellScreen.Vault` is missing from `IsMoreSurface` or from the back gesture's first
+case, and those two have to move together — the switch mirrors that property by construction.