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/visual-regression.spec.ts

@@ -10,21 +10,14 @@
  */
 
 import { test, expect } from '@playwright/test';
-import { 
-  navigateTo, 
-  waitForLoading,
-  createScenarioViaAPI,
-  deleteScenarioViaAPI,
-  startScenarioViaAPI,
-  sendTestLogs,
-  generateTestScenarioName,
-  setMobileViewport,
-  setDesktopViewport,
-} from './utils/test-helpers';
-import { testLogs } from './fixtures/test-logs';
+import { navigateTo, waitForLoading, createTestScenario, cleanupTestScenario } from './utils/test-helpers';
 import { newScenarioData } from './fixtures/test-scenarios';
 import path from 'path';
 import fs from 'fs';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
 
 // Visual regression configuration
 const BASELINE_DIR = path.join(__dirname, 'screenshots', 'baseline');