feat: Implement favorites management API; add endpoints for adding, removing, and retrieving favorites for sounds and playlists

feat: Create Favorite model and repository for managing user favorites in the database
feat: Add FavoriteService to handle business logic for favorites management
feat: Enhance Playlist and Sound response schemas to include favorite indicators and counts
refactor: Update API routes to include favorites functionality in playlists and sounds

app/core/database.py

@@ -9,6 +9,7 @@ from app.core.logging import get_logger
 from app.core.seeds import seed_all_data
 from app.models import (  # noqa: F401
     extraction,
+    favorite,
     plan,
     playlist,
     playlist_sound,