Server: send each item at the revision its ciphertext is sealed at, keep team archiving with the owner, refuse suspended accounts, and stop enrolment failing after an hour

- Pull hydrated every historical change entry with the item's current ciphertext under that entry's
  old revision. The AAD binds the revision, so a client opened it at the wrong version, failed, and
  parked its own pending edit as undecryptable. Entries an item has since moved past are left out; the
  later entry carries the same payload under the right number, and a fresh device no longer downloads
  an item once per edit it ever had.
- Deleting a team's last vault archived the team whoever deleted it, so an admin could archive it out
  from under its owner. Only the owner's delete archives it now, and TeamService.ArchiveAsync checks.
- UserStatus was checked nowhere on the request path. ActiveAccountRequirement on both policies answers
  403 account-not-active for a suspended or deprovisioned account.
- The hourly last-seen update moves xmin under the tracked user, and enrolment then saved that user
  against the stale token: a 500 for anybody enrolling more than an hour after first signing in. The
  entity is reloaded after the update.

src/DodoSSH.Contracts/PublicAPI.Unshipped.txt

@@ -1,6 +1,7 @@
 #nullable enable
 const DodoSSH.Contracts.ProblemCodes.AlreadyEnrolled = "already-enrolled" -> string!
 const DodoSSH.Contracts.ProblemCodes.ClientTooOld = "client-too-old" -> string!
+const DodoSSH.Contracts.ProblemCodes.AccountNotActive = "account-not-active" -> string!
 const DodoSSH.Contracts.ProblemCodes.EnrollmentRequired = "enrollment-required" -> string!
 const DodoSSH.Contracts.ProblemCodes.EventsUnavailable = "events-unavailable" -> string!
 const DodoSSH.Contracts.ProblemCodes.Forbidden = "forbidden" -> string!