README: rewrite USB section with three steps:
1. Auto-detect USB mount point and clone repo onto it
2. Install nautilus-extension-gnome-terminal for right-click "Open in Terminal"
3. Double-click "Run Setup.desktop" to launch wizard with sudo (no terminal needed)
Run Setup.desktop: launcher file included in the repo so it's present on the
USB automatically. Uses %k to find its own location, cds to that directory,
and runs sudo ./setup.sh in a terminal window.
https://claude.ai/code/session_017WJtGcE5jjerAQCUBWUE3H
