feat: redesign demo as dark-themed P2P chat application

- Completely rewrite App.jsx as focused chat application
- Add contact management with localStorage persistence
- Add online status detection (checks every 10s for chat.rondevu@1.0.0 service)
- Implement pooled chat service (poolSize: 10) for multiple simultaneous connections
- Add real-time P2P messaging with unique connection IDs
- Add message history per contact with auto-scrolling
- Implement identification handshake protocol for connection tracking
- Apply dark theme (#1a1a1a background, #2a2a2a cards, #4a9eff accents)
- Remove all emojis from UI elements
- Update client dependency to ^0.8.0
- Add connection status indicators

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

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

package.json

@@ -1,7 +1,7 @@
 {
   "name": "rondevu-demo",
-  "version": "0.5.0",
-  "description": "Demo application for Rondevu topic-based peer discovery and signaling",
+  "version": "2.0.0",
+  "description": "Demo application for Rondevu DNS-like WebRTC with username claiming and service discovery",
   "type": "module",
   "scripts": {
     "dev": "vite",
@@ -10,7 +10,7 @@
     "deploy": "npm run build && npx wrangler pages deploy dist --project-name=rondevu-demo"
   },
   "dependencies": {
-    "@xtr-dev/rondevu-client": "^0.7.4",
+    "@xtr-dev/rondevu-client": "^0.8.0",
     "@zxing/library": "^0.21.3",
     "qrcode": "^1.5.4",
     "react": "^18.2.0",