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/android/src/main/AndroidManifest.xml

@@ -0,0 +1,25 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+  <uses-permission android:name="android.permission.INTERNET" />
+
+  <application>
+    <!--
+      Holding notification access is the only way Android lets an app see other apps'
+      media sessions. We never read notification contents; the service only uses its
+      binding to call MediaSessionManager.getActiveSessions().
+    -->
+    <service
+      android:name=".MediaListenerService"
+      android:label="@string/now_playing_listener_label"
+      android:permission="android.permission.BIND_NOTIFICATION_LISTENER_SERVICE"
+      android:exported="false">
+      <intent-filter>
+        <action android:name="android.service.notification.NotificationListenerService" />
+      </intent-filter>
+      <!-- Only media ("real-time") notifications are relevant, so the settings screen
+           doesn't pre-tick Conversations etc. We still never read notification contents. -->
+      <meta-data
+        android:name="android.service.notification.default_filter_types"
+        android:value="ongoing" />
+    </service>
+  </application>
+</manifest>