File credentials.test.ts

packages/happy-agent/src/credentials.test.ts:None–None

import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import { mkdtempSync, rmSync, readFileSync, existsSync } from 'node:fs';
import { join } from 'node:path';
import { tmpdir } from 'node:os';