Add comprehensive tests for playlist service and refactor socket service tests

- Introduced a new test suite for the PlaylistService covering various functionalities including creation, retrieval, updating, and deletion of playlists.
- Added tests for handling sounds within playlists, ensuring correct behavior when adding/removing sounds and managing current playlists.
- Refactored socket service tests for improved readability by adjusting function signatures.
- Cleaned up unnecessary whitespace in sound normalizer and sound scanner tests for consistency.
- Enhanced audio utility tests to ensure accurate hash and size calculations, including edge cases for nonexistent files.
- Removed redundant blank lines in cookie utility tests for cleaner code.

app/api/v1/__init__.py

@@ -2,13 +2,14 @@
 
 from fastapi import APIRouter
 
-from app.api.v1 import auth, main, socket, sounds
+from app.api.v1 import auth, main, playlists, socket, sounds
 
 # V1 API router with v1 prefix
 api_router = APIRouter(prefix="/v1")
 
 # Include all route modules
+api_router.include_router(auth.router, tags=["authentication"])
 api_router.include_router(main.router, tags=["main"])
-api_router.include_router(auth.router, prefix="/auth", tags=["authentication"])
+api_router.include_router(playlists.router, tags=["playlists"])
 api_router.include_router(socket.router, tags=["socket"])
 api_router.include_router(sounds.router, tags=["sounds"])