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>

src/auth.ts

@@ -0,0 +1,60 @@
+export interface Credentials {
+  peerId: string;
+  secret: string;
+}
+
+// Fetch-compatible function type
+export type FetchFunction = (
+  input: RequestInfo | URL,
+  init?: RequestInit
+) => Promise<Response>;
+
+export class RondevuAuth {
+  private fetchFn: FetchFunction;
+
+  constructor(
+    private baseUrl: string,
+    fetchFn?: FetchFunction
+  ) {
+    // Use provided fetch or fall back to global fetch
+    this.fetchFn = fetchFn || ((...args) => {
+      if (typeof globalThis.fetch === 'function') {
+        return globalThis.fetch(...args);
+      }
+      throw new Error(
+        'fetch is not available. Please provide a fetch implementation in the constructor options.'
+      );
+    });
+  }
+
+  /**
+   * Register a new peer and receive credentials
+   */
+  async register(): Promise<Credentials> {
+    const response = await this.fetchFn(`${this.baseUrl}/register`, {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify({}),
+    });
+
+    if (!response.ok) {
+      const error = await response.json().catch(() => ({ error: 'Unknown error' }));
+      throw new Error(`Registration failed: ${error.error || response.statusText}`);
+    }
+
+    const data = await response.json();
+    return {
+      peerId: data.peerId,
+      secret: data.secret,
+    };
+  }
+
+  /**
+   * Create Authorization header value
+   */
+  static createAuthHeader(credentials: Credentials): string {
+    return `Bearer ${credentials.peerId}:${credentials.secret}`;
+  }
+}