chore: add example environment configuration file for MusicBrainz and Navidrome setup

.env.example

@@ -0,0 +1,15 @@
+# MusicBrainz authentication
+MB_USERNAME=your-musicbrainz-username
+MB_PASSWORD=your-musicbrainz-password
+
+# Export scope
+# Leave empty to export songs, albums, and artists
+# ENTITY=song
+
+# Logging
+LOG_LEVEL=INFO
+
+# Navidrome Subsonic API access
+NAVIDROME_BASE_URL=https://navidrome.example.com
+NAVIDROME_USERNAME=your-navidrome-username
+NAVIDROME_PASSWORD=your-navidrome-password