- Monitor button between callsign and TG selector
- On: reconnects with TG_MONITOR for all switch-list groups,
status shows 'Мониторинг: TG...', PTT disabled
- Talker display shows callsign and its TG
- Off: back to normal talk mode
- Check latest release on startup, show 'update available' dialog with
Update/ Later buttons
- Download APK with progress and install via ACTION_VIEW + custom
UpdateFileProvider (no androidx)
- Request unknown-app-sources permission if needed, resume download on
return to the app
