What is the playwright.config.ts file and what does it configure?

import { defineConfig, devices } from '@playwright/test';

export default defineConfig({
  // ── Test Location ─────────────────────────────────
  testDir: './tests',
  testMatch: '**/*.spec.ts',     // Test file pattern

  // ── Execution ─────────────────────────────────────
  fullyParallel: true,            // All tests run in parallel
  workers: process.env.CI ? 2 : 4, // Worker count
  retries: process.env.CI ? 2 : 0, // Retry failed tests on CI

  // ── Timeouts ──────────────────────────────────────
  timeout: 30_000,               // Per-test timeout (30s)
  expect: { timeout: 5_000 },   // Assertion timeout (5s)

  // ── Global Setup ──────────────────────────────────
  globalSetup: './global-setup.ts',
  globalTeardown: './global-teardown.ts',

  // ── Reporters ─────────────────────────────────────
  reporter: [
    ['html'],                     // HTML report
    ['list'],                     // Console output
    ['json', { outputFile: 'results.json' }],
  ],

  // ── Shared Options for All Tests ──────────────────
  use: {
    baseURL: 'https://myapp.com',
    headless: true,
    screenshot: 'only-on-failure',
    video: 'retain-on-failure',
    trace: 'retain-on-failure',
    actionTimeout: 10_000,
    navigationTimeout: 30_000,
    viewport: { width: 1280, height: 720 },
    ignoreHTTPSErrors: true,
    locale: 'en-US',
    timezoneId: 'America/New_York',
  },

  // ── Browser Projects ──────────────────────────────
  projects: [
    {
      name: 'chromium',
      use: { ...devices['Desktop Chrome'] },
    },
    {
      name: 'firefox',
      use: { ...devices['Desktop Firefox'] },
    },
    {
      name: 'webkit',
      use: { ...devices['Desktop Safari'] },
    },
    // Mobile emulation
    {
      name: 'Mobile Chrome',
      use: { ...devices['Pixel 5'] },
    },
    // Setup project (runs before tests)
    {
      name: 'setup',
      testMatch: /.*\.setup\.ts/,
    },
  ],
});