v25 — set_brightness remote command for HA-driven dimming

What's in v25

New `set_brightness` kiosk_command. Accepts fractional (`0.2`) or percentage (`20`) input. Updates the persisted `screen-brightness` pref and applies live to the running MainActivity window. Clamped to [5%, 100%].

Also absorbed at provisioning time via `--ef screen_brightness 0.2`.

HA automation example: alarm-armed dimming

```yaml

• alias: Dim bedroom kiosk on alarm armed
  trigger:

  • platform: state
    entity_id: alarm_control_panel.alarmo
    to:
    • armed_night
    • armed_home
    • armed_away
      action:
  • service: homeassistant.event
    data:
    event_type: kiosk_command
    event_data:
    device: Bedroom Dashboard
    command: set_brightness
    value: "0.2"

• alias: Restore bedroom kiosk on alarm disarmed
  trigger:

  • platform: state
    entity_id: alarm_control_panel.alarmo
    to: disarmed
    action:
  • service: homeassistant.event
    data:
    event_type: kiosk_command
    event_data:
    device: Bedroom Dashboard
    command: set_brightness
    value: "1.0"
    ```