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/playwright.config.ts

@@ -96,7 +96,7 @@ export default defineConfig({
   },
 
   // Output directory for test artifacts
-  outputDir: path.join(__dirname, 'e2e-results'),
+  outputDir: 'e2e-results',
 
   // Timeout for each test
   timeout: 60000,