feat: Add playlist management functionality and compliance checks

- Introduced a new "Playlists" column in results view with visual indicators for membership.
- Added `playlist_api.py` to handle playlist-related operations (fetch, add, remove tracks).
- Implemented `PlaylistManagerDialog` for seamless playlist addition/removal with caching.
- Integrated compliance check script (`check_agents_compliance.py`) for ensuring coding standards.
- Added extensive documentation (`playlist_membership_manager.md`) covering architecture and flow.
- Updated GUI logic and QStandardItemModel setup to include playlist data.
- Included unit tests for playlist management components and API.

tidal_dl_ng/gui/tidal_session.py

@@ -56,6 +56,8 @@ class TidalSessionMixin:
         if result:
             self._init_dl()
             self.thread_it(self.playlist_manager.tidal_user_lists)
+            # Initialize playlist membership manager
+            self.init_playlist_membership_manager()
 
     def on_logout(self) -> None:
         """Log out from TIDAL and close the application."""