fix: resolve ES modules compatibility in E2E test files

- Replace __dirname with import.meta.url pattern for ES modules compatibility
- Add fileURLToPath imports to all E2E test files
- Fix duplicate require statements in setup-verification.spec.ts
- Update playwright.config.ts to use relative path instead of __dirname

This fixes the 'ReferenceError: __dirname is not defined in ES module scope' error
when running Playwright tests in the ES modules environment.

frontend/e2e/setup-verification.spec.ts

@@ -7,6 +7,12 @@
 
 import { test, expect } from '@playwright/test';
 import { navigateTo, waitForLoading } from './utils/test-helpers';
+import path from 'path';
+import fs from 'fs';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
 
 test.describe('E2E Setup Verification', () => {
   test('frontend dev server is running', async ({ page }) => {
@@ -117,9 +123,6 @@ test.describe('Environment Variables', () => {
   });
 
   test('test data directories exist', async () => {
-    const fs = require('fs');
-    const path = require('path');
-
     const fixturesDir = path.join(__dirname, 'fixtures');
     const screenshotsDir = path.join(__dirname, 'screenshots');