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/activate.py

@@ -54,10 +54,9 @@ def gui_activate(tidal: Tidal | None = None):
     window = MainWindow(tidal=tidal)
 
     window.show()
-    # Check for updates
-    window.s_update_check.emit(True)
 
-    sys.exit(app.exec())
+    exit_code = app.exec()
+    sys.exit(exit_code)
 
 
 if __name__ == "__main__":