feat(worker): poll + reconcile stopwatch to server (admin stop/cancel)

apps/worker/src/api/sessions.ts

@@ -13,6 +13,8 @@ export function useActiveSessions() {
   return useQuery({
     queryKey: ['sessions', 'active'],
     queryFn: () => apiFetch<WorkSession[]>('/api/sessions/active'),
+    // Poll so the stopwatch converges to admin changes (stop/cancel) within ~15s.
+    refetchInterval: 15000,
   });
 }