feat(desktop): auto-recover in-progress desktop tasks on client lifecycle events

- reset stale in_progress tasks owned by a client on startup, offline, and lease expiry
- monitor tasks re-queue for another pick; publish tasks move to unknown for manual reconcile
- send startup=true flag on first heartbeat so the server can trigger recovery
- finalize the linked desktop task when a phase2 monitor callback arrives via desktop_tasks path
- short-circuit the desktop monitor attempt write after the callback already finalized it

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shared-types/src/index.ts

@@ -104,6 +104,7 @@ export interface DesktopClientHeartbeatRequest {
   client_version?: string;
   channel?: string;
   account_ids?: string[];
+  startup?: boolean;
 }
 
 export interface DesktopClientHeartbeatResponse {