Add comprehensive tests for authentication, settings, and password reset pages

- Introduced smoke tests for Login, Register, Password Reset, Password Reset Confirm, and Settings pages.
- Enhanced test coverage for all dynamic imports using mocks and added Jest exclusions for non-testable Next.js files.
- Added component-specific test files for better structure and maintainability.
- Improved test isolation by mocking navigation, providers, and rendering contexts.

frontend/src/app/admin/page.tsx

@@ -4,8 +4,10 @@
  * Protected by AuthGuard in layout with requireAdmin=true
  */
 
+/* istanbul ignore next - Next.js type import for metadata */
 import type { Metadata } from 'next';
 
+/* istanbul ignore next - Next.js metadata, not executable code */
 export const metadata: Metadata = {
   title: 'Admin Dashboard',
 };