pavlobu/deskreen — reverse-engineered prompt

Build me a desktop app called Deskreen CE that lets me use any phone, tablet, or another computer with a web browser as a second screen for my main computer. I want it to run on Mac, Windows, and Linux, and feel simple enough that a normal person can open it and immediately understand what to do.

When the app starts, it should show an easy way to connect from another device on the same local network, like a QR code and a browser link. Once connected, I should be able to share my full screen or a specific app window as a live view in the browser, with low lag and a clean interface. It should use the local network and feel private and secure.

Please also include a way to launch it with a custom local IP address, so if someone has more than one network interface they can force the app to advertise the right address. Make it production ready, packaged for desktop use, and look up any current docs online if you need to.