fix: TypeScript build errors in frontend pipeline

- Remove unused ReactNode import in useAuth.test.tsx
- Use vitest/config for defineConfig to recognize test property
- Add vitest/globals to tsconfig types for test runner globals

Frontend/vite.config.ts

@@ -1,4 +1,4 @@
-import { defineConfig } from 'vite'
+import { defineConfig } from 'vitest/config'
 import react from '@vitejs/plugin-react'
 import tailwindcss from '@tailwindcss/vite'