Advertise Tasks OpenAPI source

agent.py

@@ -67,6 +67,7 @@ class TasksApi(A2AAgent):
         "openapi_auto_agent": {
             "operation_count": len(OPERATIONS),
             "default_base_url": DEFAULT_BASE_URL,
+            "source_openapi_url": "https://tasks.a2acloud.io/openapi.json",
             "security_schemes": list(SECURITY_SCHEMES),
         }
     }