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/global-teardown.ts

@@ -11,6 +11,10 @@
 import { execSync } from 'child_process';
 import path from 'path';
 import fs from 'fs';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
 
 async function globalTeardown() {
   console.log('🧹 Starting E2E test teardown...');