feat: implement 1B domain entities/repos + 1H library API routes

1B — domain layer:
- New entities: Album, Playlist, Like, PlayHistoryEntry
- Track entity extended with album_id, genre, year fields
- New protocols: AlbumRepository, PlaylistRepository, LikeRepository, HistoryRepository
- ArtistRepository / TrackRepository protocols extended (list, count, update, get_many, etc.)
- New repos: SqlAlchemyAlbum/Playlist/Like/HistoryRepository
- Artist and track repos updated to match extended protocols

1H — library API:
- Pagination: PagedResponse[T] generic, offset-based, limit default 50 max 200
- Schemas: TrackOut, AlbumOut, ArtistOut, PlaylistOut/Create/Update,
  LikeEvent/State, HistoryIn/Out, LibrarySearchResponse
- GET/PATCH/DELETE /tracks with filters, sort, pagination
- GET /albums, /albums/{id}, /albums/{id}/tracks
- GET /artists, /artists/{id}, /artists/{id}/albums, /artists/{id}/tracks
- GET /search/library (ILIKE across tracks/albums/artists)
- Full /playlists CRUD + track add/remove (append-only version bump)
- POST /likes (append-only event log), GET /likes, GET /likes/state
- POST /history (scrobble), GET /history
- deps.py: TrackRepoDep, ArtistRepoDep, AlbumRepoDep, PlaylistRepoDep,
  LikeRepoDep, HistoryRepoDep

ruff ✅  mypy ✅  pytest 45/45 ✅

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/infrastructure/db/repositories/__init__.py

@@ -1,6 +1,10 @@
 """SQLAlchemy repository adapters implementing the domain ports."""
 
+from app.infrastructure.db.repositories.album_repository import SqlAlchemyAlbumRepository
 from app.infrastructure.db.repositories.artist_repository import SqlAlchemyArtistRepository
+from app.infrastructure.db.repositories.history_repository import SqlAlchemyHistoryRepository
+from app.infrastructure.db.repositories.like_repository import SqlAlchemyLikeRepository
+from app.infrastructure.db.repositories.playlist_repository import SqlAlchemyPlaylistRepository
 from app.infrastructure.db.repositories.refresh_token_repository import (
     SqlAlchemyRefreshTokenRepository,
 )
@@ -8,7 +12,11 @@ from app.infrastructure.db.repositories.track_repository import SqlAlchemyTrackR
 from app.infrastructure.db.repositories.user_repository import SqlAlchemyUserRepository
 
 __all__ = [
+    "SqlAlchemyAlbumRepository",
     "SqlAlchemyArtistRepository",
+    "SqlAlchemyHistoryRepository",
+    "SqlAlchemyLikeRepository",
+    "SqlAlchemyPlaylistRepository",
     "SqlAlchemyRefreshTokenRepository",
     "SqlAlchemyTrackRepository",
     "SqlAlchemyUserRepository",