fix(backend): prevent overwriting message type in chat manager to avoid empty bubbles

backend/services/chat_manager.py

@@ -46,7 +46,8 @@ class ChatConnectionManager:
                 if isinstance(message['created_at'], datetime.datetime):
                     message['created_at'] = message['created_at'].isoformat()
             
-            message["type"] = "message"
+            if "type" not in message:
+                message["type"] = "message"
             payload = json.dumps(message)
             for connection in self.active_connections[order_id]:
                 try: