Adds smart-home notifications and two reliability fixes:
- New: show notifications on your Portal from Home Assistant or any MQTT source — a title, message, and an optional icon and sound, displayed on a configurable overlay. See the smart-home docs for the message format.
- New: an MQTT command to bring up the photo-frame screensaver on demand.
- Fix: the launcher no longer loses its default-home role after a photo-frame crash, so the Portal reliably returns to the Immortal home screen.
- Fix: you can uninstall apps again from the launcher's edit mode — tap the pencil, then the red X on an app.