Connect Apple Music and Spotify-via-Last.fm on iPhone

- Local Expo module (Swift): MusicKit authorization, Music User Token via
  MusicUserTokenProvider, and live Music app now-playing while the app is
  open (MediaPlayer notifications), reported through the device endpoint
- One-tap Apple Music onboarding on iOS; Apple Music row in Settings
- Sign in with Last.fm, plus a guided Spotify-via-Last.fm flow when direct
  Spotify sign-in is capped
- Device registration moved to shared code used by Android and iOS
Not yet compiled for iOS (no Xcode here); needs an EAS build.

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

apps/mobile/modules/apple-music/src/AppleMusic.types.ts

@@ -0,0 +1,16 @@
+export type AppleMusicAuthorization = 'authorized' | 'denied' | 'restricted' | 'notDetermined' | 'unknown';
+
+export type MusicAppPlayback =
+  | { state: 'stopped' }
+  | {
+      state: 'playing' | 'paused' | 'stopped';
+      title: string;
+      artist: string;
+      album: string;
+      durationMs: number;
+      storeId: string;
+    };
+
+export type AppleMusicModuleEvents = {
+  onNowPlayingChange: (playback: MusicAppPlayback) => void;
+};

apps/mobile/modules/apple-music/src/AppleMusicModule.ts

@@ -0,0 +1,13 @@
+import { NativeModule, requireOptionalNativeModule } from 'expo';
+
+import type { AppleMusicAuthorization, AppleMusicModuleEvents, MusicAppPlayback } from './AppleMusic.types';
+
+declare class AppleMusicModule extends NativeModule<AppleMusicModuleEvents> {
+  authorizationStatus(): AppleMusicAuthorization;
+  requestAuthorization(): Promise<AppleMusicAuthorization>;
+  getUserToken(developerToken: string): Promise<string>;
+  getNowPlaying(): Promise<MusicAppPlayback>;
+}
+
+/** iOS only. null on Android, web and Expo Go, so callers must feature-check. */
+export default requireOptionalNativeModule<AppleMusicModule>('AppleMusic');