A minimal frontend for the Gateway/WebSocket loop. Authenticate once, then send messages and watch live outbound events.
这是内置的简化界面，完整 Dashboard 尚未构建。
在交互式终端运行 echo-agent dashboard build 即可启用完整界面。
This is the built-in simplified page; the full Dashboard has not been built.
Run echo-agent dashboard build in an interactive terminal to enable it.