File credentials.test.ts

test/auth/credentials.test.ts:None–None

import { describe, it, expect, beforeEach, afterEach } from 'bun:test';
import { saveCredentials, loadCredentials, clearCredentials } from '../../src/auth/credentials';
import type { CredentialFile } from '../../src/auth/types';
import { mkdirSync, rmSync, existsSync } from 'fs';