Request timeout does not cover stalled response bodies

Start in src/core.ts:564-568 to trace where fetchWithTimeout clears its timer, then read defaultParseResponse() in src/core.ts:70-91 and the timeout contract in README.md:135-154 and src/index.ts:62-69. Run the supplied stalled-response reproduction and verify that the request rejects with APIConnectionTimeoutError around the configured timeout instead of remaining pending.

Description

The documented request timeout only lasts until fetch() resolves with response headers; it does not cover reading/parsing the response body.

fetchWithTimeout() clears its timer in src/core.ts:564-568 as soon as the fetch promise settles. defaultParseResponse() reads response.json()/response.text() later (src/core.ts:70-91) with no active timer. A server that sends headers and then stalls can therefore leave the SDK promise pending indefinitely, despite README.md stating that requests time out and throw APIConnectionTimeoutError.

Reproduction

import http from 'node:http';
import Browserbase from '@browserbasehq/sdk';

const server = http.createServer((_req, res) => {
  res.writeHead(200, { 'content-type': 'application/json' });
  res.write('{'); // send headers and a partial body, then stall
});
await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve));

const address = server.address();
if (!address || typeof address === 'string') throw new Error('missing port');

const client = new Browserbase({
  apiKey: 'test',
  baseURL: `http://127.0.0.1:${address.port}`,
  timeout: 50,
  maxRetries: 0,
});

const result = await Promise.race([
  client.get('/stall').then(
    () => 'resolved',
    (error) => error.constructor.name,
  ),
  new Promise<string>((resolve) => setTimeout(() => resolve('still pending'), 250)),
]);

console.log(result); // still pending, not APIConnectionTimeoutError
server.closeAllConnections();
server.close();

Expected behavior

The request rejects with APIConnectionTimeoutError around 50 ms, including time spent receiving/parsing the body.

Actual behavior

The request remains pending after 250 ms and can hang indefinitely.

Why this matters

A partial or slow response defeats the SDK's primary bound on request duration. This can exhaust application concurrency and contradicts the timeout contract documented in README.md:135-154 and ClientOptions in src/index.ts:62-69.

Tested with Node 22.14.0 against @browserbasehq/sdk 2.18.0 / current main (b781bd7).