Add WebRTC connection manager and fix race condition

- Add RondevuConnection class for high-level WebRTC management
- Handles offer/answer exchange, ICE candidates, and data channels
- Fix race condition in answer() method (register answerer before sending ICE)
- Add event-driven API (connecting, connected, disconnected, error, datachannel, track)
- Update README with connection manager examples
- Export new connection types and classes

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

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

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@xtr-dev/rondevu-client",
-  "version": "0.3.5",
-  "description": "TypeScript client for Rondevu peer signaling and discovery server",
+  "version": "0.4.0",
+  "description": "TypeScript client for Rondevu topic-based peer discovery and signaling server",
   "type": "module",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",