KaringX/karing ? reverse-engineered prompt

Build me a simple but powerful proxy app with a clean Flutter interface, like a desktop and mobile client for sing box.

I want users to be able to add and manage proxy profiles from Clash, V2Ray, Shadowsocks, Sing box, subscriptions, and GitHub subscription links, then pick a server and turn the proxy on and off easily. It should also handle routing rules so traffic can be sent through different nodes automatically, with support for custom rule groups and node groups. Please include a beginner friendly mode so it is easy to set up right away, plus a place to view connections, settings, and routing groups.

It should work across Windows, macOS, Linux, Android, iOS, tvOS, and web if possible, and support syncing configs between devices through iCloud, local network, WebDAV, and import or export zip files. Use the current sing box docs online if you need to.