MainActivity now makes the app's only start-up permission request and tells
Dart when it finishes; the phone-location stream waits for that instead of
asking in parallel, which made Android drop the location grant.
The P3 simulator run passed, so the pre-P2 FlightControlPage, the pages only
it used and its Settings toggle are gone. The app smoke test checks the home
screen again instead of the login gate removed in July.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
