chore: fix retry when quality check failed (#3698)

Author: fengju0213

camel/societies/workforce/workforce.py

@@ -3862,6 +3862,8 @@ async def _post_task(self, task: Task, assignee_id: str) -> None:
         # Record the start time when a task is posted
         self._task_start_times[task.id] = time.time()
 
+        # Ensure assignee mapping exists for retries and follow-up handling.
+        self._assignees[task.id] = assignee_id
         task.assigned_worker_id = assignee_id
 
         task_started_event = TaskStartedEvent(