feat: export task lock via lock property in TaskWorker class

src/planai/task.py

@@ -195,6 +195,16 @@ def name(self) -> str:
         """
         return self.__class__.__name__
 
+    @property
+    def lock(self) -> threading.Lock:
+        """
+        Returns the lock object for this worker.
+
+        :return: The lock object.
+        :rtype: threading.Lock
+        """
+        return self._state_lock
+
     @property
     def last_input_task(self) -> Optional[Task]:
         """