design: update Audio tool gradient to orange-red

- Change Audio gradient from purple-blue to orange-red
- Update accent color to #f97316 (vibrant orange)
- Better differentiation from Pastel (indigo-purple)
- Orange-red gradient fits audio/music theme

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

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

components/ToolsGrid.tsx

@@ -38,8 +38,8 @@ const tools = [
     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',
+    gradient: 'gradient-orange-red',
+    accentColor: '#f97316',
     badges: ['Open Source', 'Audio Editor', 'Free'],
     icon: (
       <svg className="w-12 h-12 text-white" fill="none" stroke="currentColor" viewBox="0 0 24 24">