feat：保存关键词到message数据库

src/chat/heart_flow/heartflow_message_processor.py

@@ -57,9 +57,11 @@ async def _calculate_interest(message: MessageRecv) -> Tuple[float, bool, list[s
     with Timer("记忆激活"):
         interested_rate, keywords = await hippocampus_manager.get_activate_from_text(
             message.processed_plain_text,
-            max_depth= 5,
+            max_depth= 4,
             fast_retrieval=False,
         )
+        message.key_words = keywords
+        message.key_words_lite = keywords
         logger.debug(f"记忆激活率: {interested_rate:.2f}, 关键词: {keywords}")
 
     text_len = len(message.processed_plain_text)