Share what's playing in any Android music app

A local Expo module listens to system media sessions (the only way
Android exposes other apps' playback, gated by notification access; we
never read notifications). It filters to known music apps, debounces and
deduplicates changes, sends a heartbeat while playing, and delivers
reports through WorkManager so they survive the app being closed.

- One-screen onboarding that doubles as Google Play's prominent
  disclosure, opening straight to the app's toggle in Android settings
- Only media notifications are pre-ticked on that settings screen
- Device registration is single-flight (several screens react to the
  same permission change) and self-heals if the server revokes a token
- Sign-out revokes the phone's token; resuming sharing re-sends the
  current track immediately
- Pause controls in Settings and on the feed
- Fix invisible tab icons and labels on Android
- Keep Metro out of build output so it doesn't exhaust file watchers

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/mobile/modules/now-playing-reader/src/NowPlayingReader.types.ts

@@ -0,0 +1,14 @@
+export type NativePlayback = {
+  app: string;
+  appName: string | null;
+  state: 'playing' | 'paused' | 'stopped';
+  title: string | null;
+  artist: string | null;
+  album: string | null;
+  durationMs: number | null;
+};
+
+export type NowPlayingReaderModuleEvents = {
+  onPlaybackChange: (event: { playback: NativePlayback | null }) => void;
+  onStatusChange: (event: { status: 'unauthorized' }) => void;
+};

apps/mobile/modules/now-playing-reader/src/NowPlayingReaderModule.ts

@@ -0,0 +1,19 @@
+import { NativeModule, requireOptionalNativeModule } from 'expo';
+
+import type { NativePlayback, NowPlayingReaderModuleEvents } from './NowPlayingReader.types';
+
+declare class NowPlayingReaderModule extends NativeModule<NowPlayingReaderModuleEvents> {
+  isPermissionGranted(): boolean;
+  openPermissionSettings(): void;
+  configure(apiUrl: string, deviceToken: string, allowedPackages: string[]): void;
+  clear(): void;
+  resend(): void;
+  needsReregistration(): boolean;
+  getCurrent(): NativePlayback | null;
+}
+
+/**
+ * Android only. null on iOS, web, and in Expo Go (no custom native code there),
+ * so callers must feature-check.
+ */
+export default requireOptionalNativeModule<NowPlayingReaderModule>('NowPlayingReader');