Archive a workspace from its sidebar row, with undo (#8904)

* feat(app): archive a workspace from its sidebar row and undo it

Hovering a workspace row on desktop shows an archive button next to the
row menu. Archiving shows a toast with Undo and a Cmd/Ctrl+Z shortcut so a
mis-click costs one keystroke instead of a trip through History.

The daemon serializes archive and undo per workspace across every
connection. An undo that lands while an archive is still tearing down
aborts it at the next checkpoint and restores only the agents that archive
took down; deleting the worktree directory is the point of no return, after
which undo recreates the worktree.

* fix(server,app): close archive and undo races found in review

- An archive request now claims the workspace's archive queue before
  looking up the workspace, so an undo sent right behind it cancels it
  instead of running first and losing to the archive.
- A repeat archive of an already archived workspace no longer wipes the
  agents the earlier archive saved for undo.
- Undo no longer brings back an agent that was archived before the
  workspace archive and only loaded to read its history.
- Each local archive or undo request owns its own intent token, so a
  late response to an earlier request cannot release a newer request's
  hold on the row. An archive canceled by another client's undo puts the
  row back.
- The undo failure toast shows translated copy; the cause goes to the log.

* fix(app): keep a workspace's layout when another client restores it during the undo window

The undo window purged tabs and layout whenever it closed after a
finished archive. If another client restored the workspace before this
client's toast closed, the restored workspace lost its saved
arrangement. The archive now commits only if the workspace is still gone
when the window closes.

* fix(app): show the archived toast's Undo as a button

* fix(app): keep a workspace's agent tabs when it is opened while its undo runs

* fix(app): keep a row whose undo is running when a directory snapshot omits it

docs/agent-lifecycle.md

@@ -259,6 +259,27 @@ archived workspace. History navigation must not infer workspace lifecycle from `
 or mutate either lifecycle. The workspace route asks the daemon for authoritative recovery state;
 only the route's explicit Unarchive or Restore action changes the archived workspace.
 
+Workspace archive is undoable from the archived toast, or with Cmd/Ctrl+Z, while the toast is up.
+The daemon runs one archive lane per workspace, shared by every connection
+(`packages/server/src/server/workspace-archive-operations.ts`):
+
+| A request arrives while  | Result                                                    |
+| ------------------------ | --------------------------------------------------------- |
+| an archive runs: archive | joins the running archive                                 |
+| an archive runs: undo    | aborts the archive, waits for it to settle, then restores |
+| an undo runs: archive    | waits for the undo, then archives                         |
+| an undo runs: undo       | joins the running undo                                    |
+
+A request takes its place in the lane before its first `await`. Arrival order decides, so an undo
+sent right behind its archive still cancels it.
+
+An aborted archive stops at its next checkpoint and reports `canceled`; the undo unarchives only
+the agents that archive itself archived. Deleting the worktree directory is the point of no
+return: an undo after it recreates the worktree through workspace recovery. The client shows or
+hides the row by the latest local intent, so a late remove or upsert from a superseded request
+does not flip it back. Tabs and layout are purged only once the undo window closes with the
+archive committed.
+
 History navigation opens the selected agent without changing either archive state. Workspace
 **Restore** recovers only the workspace; the selected archived agent stays open with its callout.
 The agent's **Unarchive** runs the provider's native unarchive hook before interactive resume and

docs/keyboard-shortcuts.md

@@ -84,3 +84,10 @@ its DOM-derived scope.
 Escape interrupts an agent only in the message input or an unclaimed surface.
 A focused terminal excludes that binding. The source leaves terminal Escape alone;
 terminal Escape/Ctrl forwarding is a separate feature.
+
+## Keys shared with text editing
+
+A binding on a key the platform already uses for editing, such as Cmd/Ctrl+Z for
+workspace archive undo, declares `editable: false` and registers its handler with
+`isActive` true only while it has work. An inactive handler leaves the key
+unhandled, so the pipeline skips `preventDefault` and the platform's own undo runs.