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.
iOS + Android targets only; desktop disabled (per spec, Tauri-wrapped
SvelteKit handles desktop in v1.1). Riverpod + dio + just_audio +
audio_service + go_router pinned in pubspec. Smoke test confirms the
ProviderScope wiring boots a Material app.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>