update: rebrand Vert to Convert with improved description

- Rename tool from "Vert" to "Convert" across all files
- Update URL: vert.kit.pivoine.art → convert.kit.pivoine.art
- Improve description to highlight WebAssembly technology
- Update metadata keywords from 'vert' to 'convert'
- Better reflect actual features: videos, images, and audio conversion

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

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

components/ToolsGrid.tsx

@@ -5,9 +5,9 @@ import ToolCard from './ToolCard';
 
 const tools = [
   {
-    title: 'Vert',
-    description: 'Privacy-focused file converter that processes images, audio, and documents locally on your device. No file size limits, completely open source.',
-    url: 'https://vert.kit.pivoine.art',
+    title: 'Convert',
+    description: 'Modern browser-based file converter powered by WebAssembly. Convert videos, images, and audio locally without server uploads. Privacy-first with no file size limits.',
+    url: 'https://convert.kit.pivoine.art',
     gradient: 'gradient-green-teal',
     accentColor: '#10b981',
     badges: ['Open Source', 'Converter', 'Free'],