chore(mothership): name sign-out in desktop tool lease docs and say "not run" once

Follow-ups from the #8673 review: the lease docs now name sign-out
(`stopAllDesktopTools`) alongside the user's Stop as what cancels a desktop
tool, and the stale-observation message no longer says it was not run twice.

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/home/hooks/desktop-tool-lifetimes.ts

@@ -17,16 +17,17 @@ const runningTurns = new Map<string, RunningTurnTools>()
 
 /** A running desktop tool's hold on its turn. */
 interface DesktopToolLease {
-  /** Aborted only by the user's Stop of the turn. */
+  /** Aborted only by the user's Stop of the turn, or by signing out. */
   signal: AbortSignal
   /** Called once when the tool settles. */
   release(): void
 }
 
 /**
  * Starts a desktop tool (a browser action, a local file read or import) for a turn. Only the
- * user's Stop of that turn cancels it: replacing the stream reader, leaving the chat view, or
- * stopping another chat's turn leaves it running to finish and report its own result.
+ * user's Stop of that turn, or signing out (`stopAllDesktopTools`), cancels it: replacing the
+ * stream reader, leaving the chat view, or stopping another chat's turn leaves it running to
+ * finish and report its own result.
  */
 export function leaseDesktopTool(streamId: string): DesktopToolLease {
   let turn = runningTurns.get(streamId)

apps/sim/lib/mothership/tools/client/browser-tool-execution.test.ts

@@ -1470,7 +1470,7 @@ describe('pre-dispatch drops still resolve the waiter', () => {
     expect(mockReportCompletion).toHaveBeenCalledWith(
       'stale-call-1',
       'error',
-      expect.stringContaining('not run this time'),
+      expect.stringContaining('too late to run safely'),
       expect.objectContaining({ staleEvent: true })
     )
     const [, , message] = mockReportCompletion.mock.calls[0] ?? []

apps/sim/lib/mothership/tools/client/browser-tool-execution.ts

@@ -110,7 +110,7 @@ const OUTCOME_UNKNOWN_MESSAGE =
 const REPLAY_OUTCOME_UNKNOWN_MESSAGE =
   'This browser action was recorded before the Sim page reloaded, but its terminal result could not be recovered. It may already have taken effect. Do not retry it automatically; take a fresh browser snapshot before deciding what to do.'
 const STALE_OBSERVATION_NOT_RUN_MESSAGE =
-  'Not run: this browser observation reached the Sim desktop app too late to run safely, so it was not run this time and has no result. An observation changes nothing in the browser. Do not retry it in this turn; tell the user to keep this chat open in the Sim desktop app, or to ask again later.'
+  'Not run: this browser observation reached the Sim desktop app too late to run safely, so it has no result. An observation changes nothing in the browser. Do not retry it in this turn; tell the user to keep this chat open in the Sim desktop app, or to ask again later.'
 const STALE_STATEFUL_OUTCOME_UNKNOWN_MESSAGE =
   'This browser action was delivered too late to recover its exact result. It may already have taken effect. Do not retry it automatically; take a fresh browser snapshot before deciding what to do.'
 const REPLAY_GUARD_CAPACITY_MESSAGE =