feat(desktop): run a chat's desktop tools in the background executor

The Sim desktop app now picks up and runs the desktop tool calls of turns bound
to it from Electron main, so work keeps going when the user leaves the chat,
switches workspace, or reloads the window. It speaks the device protocol from
the previous PRs and stays dormant until Sim enables it for the user.

- Identity: a stable install id in userData, registered with the app's own
  session on sign-in and session change, retired on sign-out (which also stops
  every action and clears the outbox). A 409 mints a new id.
- Pickup: an SSE doorbell plus the reconciling inbox read on connect, on every
  ring, on wake and network return, and on Sim's reconcile timer.
- Execution: each call is claimed as soon as it is offered, queued per chat and
  surface, and run in that chat's own browser scope, terminals, or granted
  folders, from Sim's record of the call. Leases are renewed from claim to
  acknowledgement. Covers browser_*, terminal, read_local_file and user-local
  read/grep/glob; import_local_files is answered as not run for now.
- Outbox: an encrypted journal (claiming, claimed, started, result) written
  before each step. A restart reports a call that never started as not
  started, one that did as outcome unknown, and a finished one with its result;
  nothing runs twice. Results are retried with backoff until Sim answers.
- Stop: inbox cancels and refused lease renewals stop the action. Terminal runs
  get a real cancel: Ctrl-C, then SIGTERM and SIGKILL to the foreground process
  group.
- Approvals: a notification for a background chat waiting on the user, opening
  the chat at its approval card and closing once decided; it never names the
  command.
- preload exposes desktopExecutor.getDevice() so the composer binds turns.

The browser, terminal and local-filesystem result projections move from the web
app into @sim/desktop-bridge so the chat view and the executor build identical
results; the renderer behaviour is unchanged.

Author: waleedlatif1

.github/workflows/desktop-e2e.yml

@@ -84,6 +84,8 @@ jobs:
       - name: Run Playwright _electron smoke suite
         working-directory: apps/desktop
         run: bunx playwright test
+        env:
+          BACKGROUND_EXECUTOR_REPORT_PATH: test-results/background-executor-report.json
 
       - name: Upload test results
         if: failure()