zigbee2mqtt/hassio-zigbee2mqtt — reverse-engineered prompt

Build me an official Home Assistant add on repository for Zigbee2MQTT. I want someone using Home Assistant to add the repository URL in the App store, install the normal stable Zigbee2MQTT app, or choose an Edge app that follows the dev version when they need newer fixes. It should expect people to use an MQTT broker like Mosquitto, then start the app and open a web UI that guides them through picking their Zigbee USB adapter, setting the adapter type and port, and choosing the closest WiFi channel so Zigbee picks a good channel.

Please include clear install and setup docs for regular users, including Raspberry Pi 4 warning, what to do if the page briefly shows 502 Bad Gateway, where to check logs, and how to manually enter serial settings if adapter discovery fails. Also include notes for restoring data from a standalone Zigbee2MQTT install into Home Assistant, and simple local testing instructions for contributors. Look up current Home Assistant add on docs online if you need to.