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/src/lib.rs

@@ -1,11 +1,29 @@
 use tauri_plugin_sql::{Migration, MigrationKind};
 
+mod tagger;
+
 // Learn more about Tauri commands at https://tauri.app/develop/calling-rust/
 #[tauri::command]
 fn greet(name: &str) -> String {
     format!("Hello, {}! You've been greeted from Rust!", name)
 }
 
+/// Tag an audio file with metadata, cover art, and lyrics
+#[tauri::command]
+fn tag_audio_file(
+    path: String,
+    metadata: tagger::TaggingMetadata,
+    cover_data: Option<Vec<u8>>,
+    embed_lyrics: bool,
+) -> Result<(), String> {
+    tagger::tag_audio_file(
+        &path,
+        &metadata,
+        cover_data.as_deref(),
+        embed_lyrics,
+    )
+}
+
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     let migrations = vec![
@@ -58,7 +76,7 @@ pub fn run() {
         .plugin(tauri_plugin_store::Builder::new().build())
         .plugin(tauri_plugin_dialog::init())
         .plugin(tauri_plugin_fs::init())
-        .invoke_handler(tauri::generate_handler![greet])
+        .invoke_handler(tauri::generate_handler![greet, tag_audio_file])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");
 }