veyon/veyon ? reverse-engineered prompt

Build me a cross platform classroom computer management app like Veyon.

I want a teacher side app that can see all student computers at a glance, open a live view of one or more screens, and let the teacher take control when needed. It should also be able to lock student screens, send text messages, start or end lessons for everyone at once, push files, open websites or programs remotely, and power devices on, off, or reboot them. Please include the background service on the student machines and the main control app for the teacher, plus a simple setup tool for configuring everything.

Make it work on the major desktop platforms if possible, and keep it polished enough to use in a real school or training room. If you need current docs or implementation details, look them up online while you build it.