schollz/croc ? reverse-engineered prompt

Build me a simple command line app that lets two computers send files and folders to each other securely.

I want it to work on Windows, Mac, and Linux, with a very easy flow where one side runs a send command and gets a short code, then the other side uses that code to receive the transfer. The transfer should be encrypted end to end, should not need port forwarding or a local server, and it should work even if the two computers are not on the same network by using a relay.

It should support sending multiple files, folders, text, and also handle interrupted transfers by letting them resume. If possible, make it copy the code to the clipboard and show a QR code for mobile use. I would also like options for using a proxy, choosing a custom code phrase, and running your own relay.

Look up current docs online if you need to, and make it feel polished and easy to use from the terminal.