angelcam/arrow-client ? reverse-engineered prompt

Build me a small Rust app that acts like an Angelcam Arrow Client for IP cameras.

It should connect local RTSP and MJPEG camera streams to the Angelcam cloud, using a provided service address and certificate for secure TLS connection. I want to be able to pass in a fixed RTSP stream from the command line, and optionally turn on network scanning so it can discover local camera services automatically on the machine’s network interfaces.

Please make it create and use a config directory at /etc/arrow on first start, and support the extra path files for RTSP and MJPEG discovery. It should work with the custom root CA file from this repo. Also include the basic ability to register and pair devices with the user’s Angelcam account, since that seems to be part of the flow.

If anything about the current protocol details is unclear, look up the Arrow Protocol docs online and follow the reference behavior as closely as possible.