update: replace Stirling with Audio tool

- Remove Stirling PDF toolkit from tools list
- Add Audio editor (audio.kit.pivoine.art)
- Audio features: multi-track editing, effects, real-time analysis
- Export formats: WAV, MP3, OGG, FLAC
- Browser-based, privacy-first audio editing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

components/ToolsGrid.tsx

@@ -35,16 +35,15 @@ const tools = [
     ),
   },
   {
-    title: 'Stirling',
-    description: 'Powerful locally-hosted PDF toolkit with 50+ operations. Merge, split, convert, OCR, sign, and manipulate PDFs with complete privacy.',
-    url: 'https://stirling.kit.pivoine.art',
+    title: 'Audio',
+    description: 'Professional browser-based audio editor with multi-track editing, advanced effects, and real-time analysis. Record, edit, and export to WAV, MP3, OGG, or FLAC entirely in your browser.',
+    url: 'https://audio.kit.pivoine.art',
     gradient: 'gradient-purple-blue',
     accentColor: '#667eea',
-    badges: ['Open Source', 'PDF', 'Free'],
+    badges: ['Open Source', 'Audio Editor', 'Free'],
     icon: (
       <svg className="w-12 h-12 text-white" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M7 21h10a2 2 0 002-2V9.414a1 1 0 00-.293-.707l-5.414-5.414A1 1 0 0012.586 3H7a2 2 0 00-2 2v14a2 2 0 002 2z" />
-        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M10 12h4m-4 4h4" />
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 19V6l12-3v13M9 19c0 1.105-1.343 2-3 2s-3-.895-3-2 1.343-2 3-2 3 .895 3 2zm12-3c0 1.105-1.343 2-3 2s-3-.895-3-2 1.343-2 3-2 3 .895 3 2zM9 10l12-3" />
       </svg>
     ),
   },