feat(player): add local music player, configurable autoplay, and playlist sync/dedup fixes

[Arunkumar-Anbazhagan]

Summary

This PR addresses several community-requested player and playlist improvements:

1. Local Music Player: Enables LastWave to discover and play songs stored locally on the device (as well as open audio files directly from external file managers).
2. Playlist Track Deletion Index Fix: Fixes a critical bug where deleting a track while a playlist is sorted or filtered removed the wrong song.
3. Playlist Deduplication: Adds intelligent song identity matching (normalizing remasters, features, bonus tracks) and provides one-tap playlist deduplication.
4. Configurable Autoplay ("Auto-Add" Issue): Adds a user setting to control whether radio tracks automatically queue up when a playlist or queue reaches the end (defaults to false so playback stops as expected).
5. Playlist YouTube Music Sync Fix: Fixes an issue where non-exact video matches were silently dropped during remote sync passes, and enriches tracks with resolved YouTube URLs to prevent repeated resolution loops.

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Key Changes & Implementations

1. Local Music Player (feat)

• MediaStore Ingestion: Created LocalAudioRepository querying MediaStore.Audio.Media.EXTERNAL_CONTENT_URI with proper runtime permission handling (READ_MEDIA_AUDIO on Android 13+ / API 33+ and legacy storage fallback).
• Dedicated UI: Added LocalMusicScreen and LocalMusicViewModel featuring:
  • Real-time search filtering across title, artist, and album.
  • Sorting options: Recently Added, Title, Artist, and Duration.
  • Full playback controls (Play All, Shuffle, and context menu actions for queueing and playlists).
• Navigation & Entry Point: Added a Device Music navigation card in PlaylistScreen and registered the route in NavGraph and MainShell.
• System File Association / Intent Handling: Added ACTION_VIEW intent filter for audio/* in AndroidManifest.xml and handled playback with MediaMetadataRetriever in MainActivity so tapping audio files in file managers plays them directly in LastWave.

2. Playlist Track Deletion Index Fix (fix)

• Root Cause: In PlaylistDetailScreen, deleting a song passed the filtered/sorted index (displayIndex) directly to playlistRepository.removeTrackAt(), causing the wrong track to be deleted whenever the list was searched or reordered.
• Fix: Introduced IndexedDisplayTrack pairing every display track with its original unshifted index (originalIndex). Deletions now target the exact index in the underlying playlist model.

3. Song Identity Matching & Playlist Deduplication (feat/fix)

• Smart Song Matching: Added cleanCoreTitle() and cleanCoreArtist() in GeneratedTrack.kt to strip noisy metadata tags (e.g., (Remastered ...), [Deluxe Edition], feat. ..., [Official Audio]).
• One-Tap Deduplication: Added atomic deduplicate(playlistId) in PlaylistRepository and exposed it via the playlist detail menu, preserving user-pinned tracks and video IDs while eliminating duplicate entries.
• Unit Tests: Added unit tests in TrackIdentityTest.kt verifying variant matching and deduplication behavior.

4. Configurable Autoplay / Endless Queue Control (fix/feat)

• Root Cause: When a playlist reached its last track, MusicPlayer.kt unconditionally initiated an endless radio queue, injecting 35 tracks and continuing playback without user consent.
• Fix:
  • Added autoplayEnabled: Boolean = false preference in SettingsPreferences and exposed an "Autoplay similar tracks" toggle under Settings → Audio.
  • Updated MusicPlayer.kt so playback cleanly stops at the end of a queue/playlist unless the user explicitly toggles autoplay on.

5. YouTube Music Playlist Sync Drop Fix (fix)

• Root Cause: YtMusicSyncManager.kt filtered additions with && it in exactVideoIds, which dropped tracks added from Last.fm, Discover, search, or local import whose video IDs were resolved after creation.
• Fix: Removed the strict check and persisted resolved YouTube URLs (https://music.youtube.com/watch?v=$videoId) directly onto synced tracks, preventing repeated resolution calls and ensuring sync parity with remote YouTube Music playlists.
• Wrapped remote network calls and concurrent playlist mutations with non-fatal logging to prevent crashes from aborting the sync routine.

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Verification & Testing

• Unit Tests: Ran ./gradlew.bat testDebugUnitTest — all unit tests pass with zero regressions.
• Release Build: Ran ./gradlew.bat assembleRelease — compiles cleanly with R8 optimization (~23.8 MB).
• Rebase Verification: Branch is rebased cleanly on top of upstream/main (b6db40a) with linear git history and no merge conflicts.

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Modified & Added Files

• Manifest & App:
  • AndroidManifest.xml
  • MainActivity.kt
• Data & Playback:
  • LocalAudioRepository.kt (new)
  • SettingsPreferences.kt
  • YtMusicSyncManager.kt
  • PlaylistRepository.kt
  • YtMusicLibraryManager.kt
  • GeneratedTrack.kt
  • MusicPlayer.kt
• UI & Navigation:
  • LocalMusicScreen.kt (new)
  • LocalMusicViewModel.kt (new)
  • PlaylistScreen.kt
  • PlaylistDetailScreen.kt
  • PlaylistViewModel.kt
  • SettingsScreen.kt
  • SettingsViewModel.kt
  • NavGraph.kt
  • Screen.kt
  • MainShell.kt
  • PlayerHost.kt
• Tests:
  • TrackIdentityTest.kt