fix(webui): surface MCP runtime connection failures (#5331)

tests/cli/test_commands.py

@@ -84,6 +84,10 @@ class _GatewayAgentContractStub:
 
     tools = ToolRegistry()
 
+    @staticmethod
+    def mcp_runtime_status() -> dict[str, str]:
+        return {}
+
     @staticmethod
     def pending_cron_job_ids_for_session(_session_key: str) -> set[str]:
         return set()