fix usage with cloudflare workers

Cloudflare Workers (and other runtimes, including Node v22+) have a native global standards based Websocket class. This patch detects it and uses it when available.

Author: threepointone

lib/api.js

@@ -63,11 +63,11 @@ export class RealtimeAPI extends RealtimeEventHandler {
  if (this.isConnected()) {
  throw new Error(`Already connected`);
  }
- if (globalThis.document) {
+ if (globalThis.WebSocket) {
  /**
  * Web browser
  */
- if (this.apiKey) {
+ if (globalThis.document && this.apiKey) {
  console.warn(
  'Warning: Connecting using API key in the browser, this is not recommended',
  );