Refactor demo to use new ServiceHost and ServiceClient API

- Update to @xtr-dev/rondevu-client v0.10.1
- Replace Rondevu class with RondevuService, ServiceHost, ServiceClient
- Simplify demo implementation (removed complex features)
- Use new event-driven API for connections
- Support custom RTC configuration
- Backup old implementation as App-old.jsx

Breaking changes from v1 API:
- RondevuService for username claiming
- ServiceHost for hosting services with offer pool
- ServiceClient for connecting with auto-reconnection

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

package-lock.json

@@ -8,7 +8,7 @@
       "name": "rondevu-demo",
       "version": "2.0.0",
       "dependencies": {
-        "@xtr-dev/rondevu-client": "^0.10.0",
+        "@xtr-dev/rondevu-client": "^0.10.1",
         "@zxing/library": "^0.21.3",
         "qrcode": "^1.5.4",
         "react": "^18.2.0",
@@ -1171,9 +1171,9 @@
       }
     },
     "node_modules/@xtr-dev/rondevu-client": {
-      "version": "0.10.0",
-      "resolved": "https://registry.npmjs.org/@xtr-dev/rondevu-client/-/rondevu-client-0.10.0.tgz",
-      "integrity": "sha512-wCU2GhW9vhG9SDElSYdyhcvpueHcpHuOpwdqxHYgvJ/4NCHT1aIa0uHqEwLtF+aoUHbqExpLaUD8DZEnwFkZQQ==",
+      "version": "0.10.1",
+      "resolved": "https://registry.npmjs.org/@xtr-dev/rondevu-client/-/rondevu-client-0.10.1.tgz",
+      "integrity": "sha512-pQpUH7CYTiIShYplp/rv5Un0r08vDnMK2YhiNTRAc2jNzffDm+WxphalkxnmmZTm5sTMYCH9X7IQeSRmvTHcxg==",
       "license": "MIT",
       "dependencies": {
         "@noble/ed25519": "^3.0.0"