Add a Desktop toggle to the Controller (both UIs) that starts/stops
display-manager.service. Fail open: the unit is never enabled/disabled,
so the desktop always returns on reboot; users who want it disabled
across reboots can set the default target themselves.
Rename the hotspot and bluetooth actions to reflect their real behavior:
- enable/disable_hotspot -> start/stop_hotspot (/api/hotspot/start|stop)
- enable/disable_bluetooth -> unblock/block_bluetooth (rfkill semantics,
/api/bluetooth/unblock|block)
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
