- Decouples `PlayerViewModel` by delegating core responsibilities to specialized state holders: `LibraryStateHolder` for music data management, `MetadataEditStateHolder` for file modifications, and `ExternalMediaStateHolder` for URI-based playback.
- Replaces paginated library song loading with a full-list approach in `LibrarySongsTab` and `LibraryScreen` to improve sorting consistency and UI responsiveness.
- Implements `LibraryStateHolder` to centralize loading, sorting, and state management for songs, albums, artists, and folders.
- Extends `UserPreferencesRepository` and `DailyMixStateHolder` to support persisting and loading "Your Mix" song IDs.
- Enhances `AudioMetadataReader` to extract additional technical metadata including `albumArtist`, `bitrate`, and `sampleRate` using TagLib.
- Adds `getAllSongsOnce()` to `MusicRepository` and `MusicDao` for efficient one-shot retrieval of the entire music library.
- Optimizes `SortOption` by utilizing lazy initialization for static option lists.
- Fixes a potential metadata loss issue in `MetadataEditStateHolder` by explicitly preserving existing embedded artwork during text-only edits.

… item building into specialized components.

- Introduces `PlaybackStateHolder` to centralize playback controls (play/pause, seek, skip), shuffle/repeat logic, and progress tracking.
- Implements `MediaItemBuilder` to unify the creation of `MediaItem` and `MediaMetadata` with consistent extra bundle keys for song metadata.
- Migrates shuffle and queue manipulation logic to `QueueUtils`.
- Refactors `PlayerViewModel` to delegate playback state and control responsibilities to `PlaybackStateHolder`.
- Improves state synchronization between local playback and Cast sessions within the new state holder.
- Cleans up `PlayerViewModel` by removing redundant constants and helper methods now managed by utility classes.

…e media server foreground management.

- **Refactor Cast Logic**:
    - Extracts Cast session management and playback transfer logic from `PlayerViewModel` into a new `CastTransferStateHolder`.
    - Centralizes remote status updates, queue synchronization, and the "transfer back" logic to local playback.
    - Simplifies `PlayerViewModel` by delegating remote playback commands and state observation to the new holder.

- **Enhance Media Server**:
    - Updates `MediaFileHttpServerService` to automatically start as a foreground service with a persistent notification.
    - Adds `foregroundServiceType="mediaPlayback"` to the manifest for the HTTP server to comply with Android's foreground service requirements.

- **Player Engine Robustness**:
    - Introduces an `initialize()` method in `DualPlayerEngine` to safely handle player recreation if the service is restarted.
    - Ensures `MusicService` calls `engine.initialize()` during `onCreate` to guarantee the underlying `ExoPlayer` instances are ready.
    - Adds safety checks in `DualPlayerEngine.release()` to prevent null pointer exceptions on uninitialized players.

…izing logic into dedicated state holders and externalizing data models.

- **Modularize ViewModels**:
    - Moves `PlayerUiState`, `StablePlayerState`, `PlayerSheetState`, `ColorSchemePair`, and `LyricsSearchUiState` into separate files for better maintainability and code organization.
    - Introduces `ThemeStateHolder` to manage album art color extraction, dynamic palette generation, and the "lava lamp" background colors.
    - Relocates genre generation logic and state into `LibraryStateHolder`.
    - Moves repeat mode management and shuffle preparation logic into `PlaybackStateHolder` and `QueueStateHolder` respectively.

- **Enhance Theme Processing**:
    - Implements an asynchronous color scheme extraction flow in `ThemeStateHolder` using a centralized `ColorSchemeProcessor`.
    - Adds `getAlbumColorSchemeFlow()` with LRU caching to efficiently handle per-album color palettes in list views (e.g., `LibraryScreen`).

- **Improve Playback Logic**:
    - Refactors `playSongsShuffled` to use `QueueStateHolder` for Atomic queue preparation, preventing race conditions during shuffle transitions.
    - Centralizes repeat mode updates (Off/One) into `PlaybackStateHolder.setRepeatMode()`, ensuring consistency across local and Cast playback.
    - Automates lyrics sync offset updates in `LyricsStateHolder` by observing song changes within its initialization.

- **UI Refinement**:
    - Updates `LibraryScreen` to utilize the new `ThemeStateHolder` for fetching album-specific color schemes.
    - Cleans up `PlayerViewModel` by removing redundant state variables and delegating implementation details to injected helper classes.

…e holders and helper classes

- Introduces `ImageCacheManager` to centralize Coil image cache invalidation for cover art.
- Introduces `MediaMapper` to handle the conversion of `MediaItem` objects to `Song` models.
- Refactors `PlayerViewModel` by delegating Google Cast discovery and management logic to `CastStateHolder`.
- Enhances `LyricsStateHolder` to manage remote lyrics fetching, manual searching, and file importing, reducing the ViewModel's responsibility.
- Replaces inline MediaRouter callback logic in `PlayerViewModel` with a more robust implementation within `CastStateHolder`.
- Updates `PlayerViewModel` to observe song and message events from `LyricsStateHolder` for UI synchronization.
- Simplifies `resolveSongFromMediaItem` and `invalidateCoverArtCaches` by utilizing the new helper classes.

- Updates `MainActivity` to use real library data instead of dummy data when benchmarking.
- Significantly reduces `PlayerViewModel` complexity by removing unused imports, constants, and private helper functions.
- Streamlines `PlayerViewModel` initialization and data loading by delegating more responsibilities to specialized state holders (e.g., `LibraryStateHolder`, `ThemeStateHolder`).
- Removes redundant or unused state flows like `paginatedSongs`, `isSheetVisible`, and `playerThemePreference`.
- Cleans up playback logic, removing unused methods for repeat modes and redundant queue matching helpers.
- Simplifies theme preloading and library data fetching, utilizing parallel execution via delegated holders.
- Removes manual artwork loading logic in favor of existing infrastructure.
- Deletes dead code related to folder filtering and old benchmark data generation.