fix: exclude e2e directory from vitest to prevent playwright test conflicts

frontend/vitest.config.ts

@@ -13,6 +13,7 @@ export default defineConfig({
     globals: true,
     environment: 'jsdom',
     setupFiles: ['./tests/setup.ts'],
+    exclude: ['node_modules/**', 'e2e/**', '.next/**'],
     coverage: {
       provider: 'v8',
       reporter: ['text', 'html'],