feat(ui): worker-menu Shutdown ends worker + app after confirm

Adds a Shutdown entry after the Worker menu's Restart/Update Claude CLI
items. Confirms via IDialogService.ConfirmAsync, then kills this
installation's ClaudeDo.Worker process(es) (shared kill loop, extracted
from RestartWorkerService) and force-closes the window through the same
_forceClose path MainWindow already uses for the Mission-Control close
confirm, so no second confirmation dialog shows.

src/ClaudeDo.Localization/locales/en.json

@@ -785,6 +785,7 @@
       "checkForUpdates": "Check for updates",
       "restartWorker": "Restart worker",
       "updateClaudeCli": "Update Claude CLI",
+      "shutdown": "Shutdown",
       "worktrees": "Worktrees…",
       "weeklyReport": "Weekly Report…",
       "usageMonitor": "Usage Monitor…",
@@ -810,7 +811,7 @@
   },
   "vm": {
     "connection": { "online": "Online", "connecting": "Connecting…", "offline": "Offline" },
-    "shell": { "unexpectedError": "Unexpected error: {0}" },
+    "shell": { "unexpectedError": "Unexpected error: {0}", "shutdownConfirm": "This stops the ClaudeDo worker (any running task or interactive session is interrupted) and closes the app. Continue?" },
     "mainWindow": { "closeConfirm": { "message": "{0} Mission Control session(s) are still running. Closing the app will end them. Close anyway?" } },
     "agentStatus": { "idle": "Idle", "queued": "Queued", "running": "Running", "review": "Review", "children": "Waiting for Subtasks", "done": "Done", "failed": "Failed", "cancelled": "Cancelled" },
     "taskStatus": { "idle": "Idle", "queued": "Queued", "running": "Running", "waitingForReview": "Waiting for Review", "waitingForChildren": "Waiting for Subtasks", "done": "Done", "failed": "Failed", "cancelled": "Cancelled", "parked": "Parked", "interactive": "Interactive", "waiting": "Waiting" },