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>

src/index.ts

@@ -16,18 +16,12 @@ export { RondevuAPI } from './client.js';
 export type {
   // WebRTC types
   RondevuOptions,
-  JoinOptions,
   ConnectionRole,
   RondevuConnectionParams,
   RondevuConnectionEvents,
   WebRTCPolyfill,
   // Signaling types
   Side,
-  Session,
-  TopicInfo,
-  Pagination,
-  ListTopicsResponse,
-  ListSessionsResponse,
   CreateOfferRequest,
   CreateOfferResponse,
   AnswerRequest,