polish: Priority 1 improvements - gradients, stats, metadata, footer

✨ Visual Enhancements:
- Unique gradients per tool (green-teal for Vert, orange-pink for Paint, indigo-purple for Pastel)
- Added new gradient utilities for better color differentiation

📊 Stats Section:
- New animated stats component showing "3 Tools, 100% Open Source, ∞ Privacy First"
- Glassmorphism cards with hover effects
- Icon badges for each stat

🔍 Enhanced Metadata:
- Comprehensive Open Graph tags for social sharing
- Twitter Card support
- Enhanced SEO with detailed keywords (vert, paint, pastel)
- Added SVG favicon with gradient toolbox icon
- Viewport meta tag and preconnect optimization

🔗 Improved Footer:
- 3-column responsive layout
- GitHub repository link with icon
- Quick links to all tools (Vert, Paint, Pastel)
- Tool count badge
- Updated tech stack mention (Next.js 16 & Tailwind CSS 4)

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

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

components/ToolsGrid.tsx

@@ -8,7 +8,7 @@ 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',
-    gradient: 'gradient-purple-blue',
+    gradient: 'gradient-green-teal',
     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="M4 16l4.586-4.586a2 2 0 012.828 0L16 16m-2-2l1.586-1.586a2 2 0 012.828 0L20 14m-6-6h.01M6 20h12a2 2 0 002-2V6a2 2 0 00-2-2H6a2 2 0 00-2 2v12a2 2 0 002 2z" />
@@ -19,7 +19,7 @@ const tools = [
     title: 'Paint',
     description: 'An advanced image editor running in your browser. Edit photos, create graphics, and more.',
     url: 'https://paint.kit.pivoine.art',
-    gradient: 'gradient-cyan-purple',
+    gradient: 'gradient-orange-pink',
     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 21a4 4 0 01-4-4V5a2 2 0 012-2h4a2 2 0 012 2v12a4 4 0 01-4 4zm0 0h12a2 2 0 002-2v-4a2 2 0 00-2-2h-2.343M11 7.343l1.657-1.657a2 2 0 012.828 0l2.829 2.829a2 2 0 010 2.828l-8.486 8.485M7 17h.01" />
@@ -30,7 +30,7 @@ const tools = [
     title: 'Pastel',
     description: 'Modern color manipulation toolkit with palette generation, accessibility testing, and format conversion. Supports hex, RGB, HSL, Lab, and more.',
     url: 'https://pastel.kit.pivoine.art',
-    gradient: 'gradient-purple-blue',
+    gradient: 'gradient-indigo-purple',
     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 21a4 4 0 01-4-4V5a2 2 0 012-2h4a2 2 0 012 2v12a4 4 0 01-4 4zm0 0h12a2 2 0 002-2v-4a2 2 0 00-2-2h-2.343M11 7.343l1.657-1.657a2 2 0 012.828 0l2.829 2.829a2 2 0 010 2.828l-8.486 8.485M7 17h.01" />