v2.2.0

v2.2.0 — FFmpeg 8.0.1 on Pi 5, RAM-mode warning at wizard launch

- 10-install-drup: FFmpeg 8.0.1 minimal confirmed working on Pi 5
- FFmpeg menu references updated for DRUP v2.5.7
- setup.sh now warns before any action when the running session discards
  writes on reboot (overlayfs: everything is lost; systemd.volatile: /var
  only), so a full install — or a git pull — can no longer evaporate
  silently at the next boot. Detection reads /proc/cmdline (the kernel
  actually running), not grubby (which reports the next boot).

RAM-mode warning reported by Auke.