Add initial project files for MusicBrainz Missing Albums Finder

- Created .gitignore to exclude unnecessary files and directories.
- Added flake.nix for Nix package management and development environment setup.
- Introduced flake.lock to lock dependencies for reproducibility.
- Implemented main.py script to identify missing albums on MusicBrainz from Deezer releases for artists monitored in Lidarr, including functionality for generating submission links.

.gitignore

@@ -0,0 +1,28 @@
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+env/
+venv/
+ENV/
+.venv
+
+# Environment variables
+# Note: .env is NOT ignored by default so you can commit a template
+# If you want to ignore your actual .env, uncomment the line below
+# .env
+
+# Output files
+missing_albums.json
+missing_albums.html
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+.env
+