smoke_test was hanging in pumpAndSettle because real
flutter_secure_storage MethodChannel calls don't resolve in widget
tests (no platform channel registered). Override secureStorageProvider
with a mocktail FlutterSecureStorage that returns null for every read,
so the GoRouter redirect resolves and ServerUrlScreen renders.
player_provider_test second case was crashing because constructing
MinstrelAudioHandler() instantiates just_audio's AudioPlayer, which
calls setMethodCallHandler during construction — that asserts unless
the WidgetsFlutterBinding is initialized. Add
TestWidgetsFlutterBinding.ensureInitialized() at the top of main().
Both are unit-test plumbing fixes; no production code change.
audio_service runs the handler in a background isolate; UI watches
playbackState/mediaItem/queue streams through Riverpod. AndroidManifest
gets the foreground-service media-playback permission; Info.plist gets
UIBackgroundModes=audio. Bearer token attached to stream URLs via
just_audio's per-source headers.
bvandeusen