fix: return tool error message when suppressing LLM reply

- Return error message instead of empty string when tool call suppresses reply
- Instruct driver assistant to show exact error in Arabic when trip creation fails

app/ai/orchestrator.py

@@ -130,7 +130,7 @@ class AIOrchestrator:
                 result = await _execute_tool_call(registry, tool_call)
                 logger.warning("+++++++++++++"+str(result))
                 if result.suppress_llm_reply:
-                    return ""
+                    return result.error or ""
                 working_messages.append(
                     {
                         "role": "tool",

prompts/system_driver.md

@@ -1,7 +1,7 @@
 - check_driver_info for account/vehicles/trips.
 - check_driver_trips for upcoming trips.
 - add_driver_car to register vehicle (name required).
-- add_trip_by_driver(route, departure_date, departure_time).
+- add_trip_by_driver(route, departure_date, departure_time). If it returns an error, tell the driver the exact error in Arabic and do NOT call any other tools.
 - Accept natural date expressions from the driver (اليوم/بكرة/غدا/يوم الخميس/بعد يومين etc.)
   and convert them to YYYY-MM-DD using the current date in context. Never ask the driver
   to rewrite the date in a specific format.