Add audio verification and duplicate tracking features

- Integrated `plexapi` and `python-dotenv` as dependencies in `flake.nix` and `pyproject.toml` for enhanced functionality.
- Implemented new modules for audio verification and duplicate tracking, including `audio_verification.py`, `duplicate_finder.py`, and `track_verification.py`.
- Updated `main.py` to utilize the new modules for identifying and managing duplicate single tracks in Lidarr, with detailed logging and confidence scoring.
- Enhanced the `find_duplicate_singles` function to support audio verification results and metadata migration to Plex.
- Refactored existing code for improved structure and maintainability, ensuring better integration of new features.

nix/package-cleanup.nix

@@ -11,6 +11,7 @@ pkgs.python3Packages.buildPythonApplication {
   propagatedBuildInputs = with pkgs.python3Packages; [
     requests
     python-dotenv
+    plexapi
   ];
   
   # Runtime dependencies for audio verification