Kód szerkesztés és refaktorálás AI-val

@src/store/userStore.ts
@src/hooks/useUser.ts
@src/components/UserProfile.tsx

The userStore is using local state for authentication.
Refactor it to use Zustand with persist middleware.
Update all related hooks and components to use the new store.
Don't change the existing component API.

I'm getting this error in the console:

TypeError: Cannot read properties of undefined (reading 'map')
  at ProductList.tsx:34:23

@src/components/ProductList.tsx

The data is fetched with React Query. Find the root cause
and add proper null/loading state handling.

@src/utils/formatCurrency.ts

Write comprehensive unit tests for this utility function using
Vitest. Cover edge cases: null input, negative numbers,
different currencies, and locale formatting.

@src/api/ordersApi.ts

Generate JSDoc comments for all exported functions.
Include parameter descriptions, return types, and
usage examples for complex functions.

@src/middleware/auth.ts

Explain how this middleware works step by step.
What security assumptions does it make?
Are there any potential vulnerabilities?

@src/services/paymentService.ts

Review this code for:
1. Potential race conditions
2. Error handling completeness
3. Security issues
4. Performance bottlenecks

Suggest concrete improvements with code examples.