Add remote volume control for the living room media center (boxy) that
controls the Denon AVR through Home Assistant instead of local audio.
- Create plasma-manager-kodi role with custom KDE hotkeys for volume
up/down/mute that execute shell scripts
- Scripts retrieve HA token from KDE Wallet and send API requests to
control media_player.denon_avr_s970h_2
- Add retry logic (3 attempts) and error notifications
- Enable KDE Wallet PAM integration for automatic wallet unlock
- Configure KDE settings: Breeze Dark theme, disable screen locking,
empty session restore
- Add kconfig package for debugging tools
