feat: add dark mode, fuzzy search, favorites, and URL sharing

Implemented Phases 5-7 of the implementation plan with major UX enhancements:

**Dark Mode (Phase 9)**
- Added ThemeToggle component with localStorage persistence
- System preference detection
- Smooth theme transitions
- Moon/Sun icon toggle in header

**Fuzzy Search with Fuse.js (Phase 5)**
- Integrated Fuse.js for intelligent font search
- 30% threshold for flexible matching
- Search by font name and filename
- Clear button for search input
- Much better than simple string matching

**Favorites & Recent Fonts System (Phase 7)**
- localStorage-based favorites with heart icon toggle
- Auto-tracking of recently used fonts (max 10)
- Filter tabs: All / Favorites / Recent
- Favorite hearts visible on hover
- Red filled heart for favorited fonts
- Stats showing favorite and recent counts

**Shareable URLs (Phase 6)**
- Encode text + font in URL parameters
- Auto-load from URL on page load
- Share button copies URL to clipboard
- Clean URL updates without page reload
- Perfect for sharing ASCII art creations

**Enhanced Font Selector**
- 3-tab filter system (All/Favorites/Recent)
- Visual feedback for selected fonts
- Empty states for each filter
- Font count statistics
- Heart icon for quick favoriting
- Recent fonts sorted by usage order

**UX Improvements**
- Copy feedback ("Copied to clipboard! ✓")
- Share feedback ("URL copied to clipboard! ✓")
- Responsive button layout
- Better empty states
- Improved accessibility with aria-labels

**Tech Highlights**
- Client-side localStorage management
- URL encoding/decoding utilities
- React hooks for state management
- Fuse.js fuzzy search integration
- Theme persistence across sessions

The app now has professional-grade features rivaling any modern web app!

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

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

app/page.tsx

@@ -1,14 +1,18 @@
 import { FigletConverter } from '@/components/converter/FigletConverter';
+import { ThemeToggle } from '@/components/layout/ThemeToggle';
 
 export default function Home() {
   return (
     <main className="min-h-screen p-4 sm:p-8">
       <div className="max-w-7xl mx-auto">
-        <header className="mb-8">
-          <h1 className="text-3xl sm:text-4xl font-bold mb-2">Figlet UI</h1>
-          <p className="text-sm sm:text-base text-muted-foreground">
-            ASCII Art Text Generator with 373 Fonts
-          </p>
+        <header className="mb-8 flex items-start justify-between">
+          <div>
+            <h1 className="text-3xl sm:text-4xl font-bold mb-2">Figlet UI</h1>
+            <p className="text-sm sm:text-base text-muted-foreground">
+              ASCII Art Text Generator with 373 Fonts
+            </p>
+          </div>
+          <ThemeToggle />
         </header>
 
         <FigletConverter />