feat: Rust audio engine, genre mix, queue shuffle, and UX improvements (v1.2.0)

### Audio Engine
- Replace Howler.js with native Rust/rodio backend (src-tauri/src/audio.rs)
- audio_play/pause/resume/stop/seek/set_volume Tauri commands
- Generation counter cancels stale in-flight downloads on skip
- Wall-clock position tracking; audio:ended after 2 ticks near end

### Playback Persistence
- Persist currentTrack, queue, queueIndex, currentTime to localStorage
- Cold-start resume: play + seek to saved position on app restart
- Position priority: server queue > localStorage

### Random Mix
- Genre blacklist: excludeAudiobooks toggle + custom chip-based blacklist
- Clickable genre chips in tracklist to blacklist on the fly
- Super Genre Mix: 9 genres, progressive rendering, Load 10 more
- Promise.allSettled + 45s timeout for large Metal/Rock libraries
- Two-column filter panel at top of page

### Queue & UI
- Shuffle button in queue header (Fisher-Yates, keeps current track at 0)
- LiveSearch arrow key / Enter / Escape keyboard navigation
- Multi-line tooltip support (data-tooltip-wrap attribute)
- Update link uses Tauri shell open() to launch system browser
- Sidebar min-width 180px → 200px (fixes Psysonic title clipping)
- Tooltip z-index fix: main-content z-index:1 over queue panel

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

src/components/QueuePanel.tsx

@@ -1,6 +1,6 @@
 import React, { useState, useRef } from 'react';
 import { Track, usePlayerStore } from '../store/playerStore';
-import { Play, Music, Star, X, Trash2, Save, FolderOpen } from 'lucide-react';
+import { Play, Music, Star, X, Trash2, Save, FolderOpen, Shuffle } from 'lucide-react';
 import { buildCoverArtUrl, getAlbum, getPlaylists, getPlaylist, createPlaylist, deletePlaylist, SubsonicPlaylist } from '../api/subsonic';
 import { useEffect } from 'react';
 import { useTranslation } from 'react-i18next';
@@ -122,6 +122,7 @@ export default function QueuePanel() {
   const clearQueue = usePlayerStore(s => s.clearQueue);
 
   const reorderQueue = usePlayerStore(s => s.reorderQueue);
+  const shuffleQueue = usePlayerStore(s => s.shuffleQueue);
   const enqueue = usePlayerStore(s => s.enqueue);
 
   const [draggedIdx, setDraggedIdx] = useState<number | null>(null);
@@ -247,6 +248,9 @@ export default function QueuePanel() {
         <h2 style={{ fontSize: '14px', fontWeight: 600, margin: 0 }}>{t('queue.title')}</h2>
         
         <div style={{ display: 'flex', alignItems: 'center', gap: '8px' }}>
+          <button onClick={() => shuffleQueue()} style={{ color: 'var(--text-muted)', cursor: 'pointer', display: 'flex' }} aria-label={t('queue.shuffle')} data-tooltip={t('queue.shuffle')} disabled={queue.length < 2}>
+            <Shuffle size={14} />
+          </button>
           <button onClick={handleSave} style={{ color: 'var(--text-muted)', cursor: 'pointer', display: 'flex' }} aria-label={t('queue.savePlaylist')} data-tooltip={t('queue.save')}>
             <Save size={14} />
           </button>