feat: integrate lyrics module with UI

- Add lyricsStore for frontend state management with LRC parsing
- Wire LyricsSidebar to main layout with toggle button in NowPlayingBar
- Fix Rust compile errors (add Clone to LrclibItem, remove unused import)
- Add lyrics active line tracking with binary search
- Auto-start/stop lyrics updates based on playback state

src-tauri/src/lyrics/mod.rs

@@ -7,7 +7,6 @@ pub mod commands;
 pub mod providers;
 
 use serde::{Deserialize, Serialize};
-use std::path::PathBuf;
 use std::sync::Arc;
 use tokio::sync::Mutex;
 

src-tauri/src/lyrics/providers.rs

@@ -13,7 +13,7 @@ pub struct LyricsData {
     pub provider: LyricsProvider,
 }
 
-#[derive(Debug, Deserialize)]
+#[derive(Debug, Clone, Deserialize)]
 #[serde(rename_all = "camelCase")]
 struct LrclibItem {
     #[serde(default)]