booking: disable send_ready until messaging 2FA is resolved

room_cal/service_api/_booking.py

@@ -587,7 +587,7 @@ class _BookingClient:
     ]
 
   def send_ready(self) -> bool:
-    return True
+    return False
 
   async def get_thread(self, reservation_id: str) -> BookingThread:
     """Fetch a conversation thread and its messages by reservation ID."""