fix: font switching, layout scaling, embedded lyrics, folder opening

- fix(fonts): update CSS var declarations to @fontsource-variable naming
  ('Inter Variable', 'Outfit Variable', etc.) so dynamic font switching works
- fix(layout): 100vh → 100% on .app-shell to fix Windows WebView2 playerbar drift;
  1fr → minmax(0,1fr) in all grid-template-rows + remove min-height: 720px to fix
  Linux playerbar disappearing at high zoom or small window sizes
- fix(updater): replace shell open() with Rust open_folder command to bypass
  shell:allow-open capability scope blocking local paths on Windows
- fix(lyrics): add get_embedded_lyrics Tauri command (id3 crate for MP3 SYLT/USLT,
  lofty for FLAC SYNCEDLYRICS/LYRICS); fix parseLrc regex for LRC without fractional
  seconds; fix SubsonicStructuredLyrics to accept both synced and issynced fields

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/api/lrclib.ts

@@ -36,7 +36,9 @@ export async function fetchLyrics(
 export function parseLrc(lrc: string): LrcLine[] {
   const lines: LrcLine[] = [];
   for (const line of lrc.split('\n')) {
-    const match = line.match(/^\[(\d+):(\d+\.\d+)\](.*)/);
+    // \d+(?:\.\d*)? — decimal part is optional so [mm:ss] (no fraction) also matches.
+    // parseFloat handles all forms: "15", "15.", "15.3", "15.32" correctly.
+    const match = line.match(/^\[(\d+):(\d+(?:\.\d*)?)\](.*)/);
     if (!match) continue;
     const mins = parseInt(match[1], 10);
     const secs = parseFloat(match[2]);