refactor: migrate audio metadata tagging from ts to rust

- Add id3 and metaflac crates for native audio tagging
- Create tagger.rs with separate tag_mp3() and tag_flac() functions
- Implement tag_audio_file Tauri command for unified tagging interface
- Support full metadata: title, artist, album, track#, ISRC, BPM, lyrics, cover art
- Create TypeScript wrapper (tagger.ts) for calling Rust backend
- Update downloader.ts to use Rust tagging for both MP3 and FLAC
- Remove browser-id3-writer dependency (no browser FLAC support)
- Inline lyrics parsing in addToQueue.ts (no longer needed in tagger)

src-tauri/Cargo.toml

@@ -27,4 +27,6 @@ serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 tauri-plugin-http = { version = "2", features = ["unsafe-headers"] }
 tauri-plugin-sql = { version = "2", features = ["sqlite"] }
+id3 = "1.16.3"
+metaflac = "0.2.8"