Update dialogue_manager: add warning when message is empty

dialogue_manager.py

@@ -290,6 +290,7 @@ class DialogueManager:
     def _determine_state_from_message(self, message_text: Optional[str]) -> DialogueState:
         """根据消息内容确定对话状态"""
         if not message_text:
+            logger.warning(f"staff[{self.staff_id}], user[{self.user_id}]: empty message")
             return self.current_state
         # 简单的规则-关键词匹配
         message_lower = message_text.lower()