fix(chat): remove redundant and undefined payload variable in message posting

backend/routers/chat.py

@@ -57,8 +57,6 @@ async def post_order_message(order_id: int, data: schemas.MessageCreate, user: d
 
     message = data.message.strip()
     if not message: raise HTTPException(status_code=400, detail="Empty message")
-    role = payload.get("role")
-    user_id = payload.get("id")
     is_admin = (role == 'admin')
     
     if not is_admin: