v24 — silence button actually disarms HA

What's in v24

The SILENCE SIREN button on the AlarmActivity overlay used to just stop the local siren. Now it calls HA's `alarm_control_panel.alarm_disarm` service. The resulting state change propagates over the WebSocket to every connected kiosk and each one auto-dismisses its overlay via the v23 onAlarmCleared path -- so one tap on a designated panel silences and dismisses the alarm fleet-wide.

`alarm_can_disarm` and `alarm_disarm_code` can now be set at provisioning time via intent extras (`--ez alarm_can_disarm true --es alarm_disarm_code 1234`) or remotely via the `set_can_disarm` / `set_disarm_code` kiosk_command events.

Practical pattern: enable siren on every room, set `can-disarm=true` only on the master bedroom panel. Anywhere in the house, the alarm fires loud and visible. Only the bedroom can silence it -- and one tap on the bedroom panel kills the alarm everywhere.