Simplify client: remove topics, ID-based connections only

- Remove join(), listTopics(), listSessions() methods
- Simplify to just create(id) and connect(id)
- Remove topic-related types and interfaces
- Add automatic version checking against server
- Update README with simplified API
- Client version: 0.3.2

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

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@xtr-dev/rondevu-client",
-  "version": "0.3.1",
+  "version": "0.3.2",
   "description": "TypeScript client for Rondevu peer signaling and discovery server",
   "type": "module",
   "main": "dist/index.js",