Add favicon and improve demo page

- Add SVG favicon with privacy shield design
- Include standard .ico favicon for browser compatibility
- Add git repository link to demo page for easy access
- Clean up meta tags and remove unnecessary PWA complexity

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

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

favicon.svg

@@ -0,0 +1,23 @@
+<svg width="32" height="32" viewBox="0 0 32 32" xmlns="http://www.w3.org/2000/svg">
+  <defs>
+    <linearGradient id="gradient" x1="0%" y1="0%" x2="100%" y2="100%">
+      <stop offset="0%" style="stop-color:#667eea;stop-opacity:1" />
+      <stop offset="100%" style="stop-color:#764ba2;stop-opacity:1" />
+    </linearGradient>
+  </defs>
+  
+  <!-- Background circle -->
+  <circle cx="16" cy="16" r="15" fill="url(#gradient)" stroke="#fff" stroke-width="1"/>
+  
+  <!-- Shield shape representing privacy protection -->
+  <path d="M16 4 L12 6 L12 14 Q12 18 16 21 Q20 18 20 14 L20 6 Z" fill="white" opacity="0.9"/>
+  
+  <!-- Lock symbol inside shield -->
+  <rect x="14" y="12" width="4" height="4" rx="0.5" fill="url(#gradient)"/>
+  <path d="M14.5 12 Q14.5 10.5 16 10.5 Q17.5 10.5 17.5 12" fill="none" stroke="url(#gradient)" stroke-width="1"/>
+  
+  <!-- Small tracking dots -->
+  <circle cx="10" cy="26" r="1.5" fill="#4caf50" opacity="0.8"/>
+  <circle cx="22" cy="26" r="1.5" fill="#667eea" opacity="0.8"/>
+  <circle cx="16" cy="28" r="1" fill="#764ba2" opacity="0.6"/>
+</svg>