Refactor to enforce AuthContext usage over useAuthStore and improve test stability

- Replaced `useAuthStore` with `useAuth` from `AuthContext` across frontend components and tests to ensure dependency injection compliance.
- Enhanced E2E test stability by delaying navigation until the auth context is fully initialized.
- Updated Playwright configuration to use a single worker to prevent mock conflicts.
- Refactored test setup to consistently inject `AuthProvider` for improved isolation and mocking.
- Adjusted comments and documentation to clarify dependency injection and testability patterns.

frontend/tests/lib/api/hooks/useUser.test.tsx

@@ -7,6 +7,7 @@ import { renderHook, waitFor } from '@testing-library/react';
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
 import { useUpdateProfile } from '@/lib/api/hooks/useUser';
 import { useAuthStore } from '@/lib/stores/authStore';
+import { AuthProvider } from '@/lib/auth/AuthContext';
 import * as apiClient from '@/lib/api/client';
 
 // Mock dependencies
@@ -32,7 +33,9 @@ describe('useUser hooks', () => {
 
   const wrapper = ({ children }: { children: React.ReactNode }) => (
     <QueryClientProvider client={queryClient}>
-      {children}
+      <AuthProvider>
+        {children}
+      </AuthProvider>
     </QueryClientProvider>
   );