fix：修复获取最近的历史消息的bug

src/backend/bisheng/database/models/message.py

@@ -91,7 +91,7 @@ def get_latest_message_by_chat_ids(cls, chat_ids: list[str], category: str = Non
         statement = select(ChatMessage).where(ChatMessage.chat_id.in_(chat_ids))
         if category:
             statement = statement.where(ChatMessage.category == category)
-        statement = statement.order_by(ChatMessage.create_time.desc()).limit(1)
+        statement = statement.order_by(ChatMessage.create_time.desc())
         with session_getter() as session:
             return session.exec(statement).all()