Add tests for AuthGuard, Skeleton components, and AdminPage

- Enhance `AuthGuard` tests with 150ms delay skeleton rendering.
- Add new test files: `Skeletons.test.tsx` to validate skeleton components and `admin/page.test.tsx` for admin dashboard.
- Refactor `AuthGuard` tests to utilize `jest.useFakeTimers` for delay simulation.
- Improve coverage for loading states, fallback behavior, and rendering logic.

frontend/tests/app/admin/page.test.tsx

@@ -0,0 +1,73 @@
+/**
+ * Tests for Admin Dashboard Page
+ * Verifies rendering of admin page placeholder content
+ */
+
+import { render, screen } from '@testing-library/react';
+import AdminPage from '@/app/admin/page';
+
+describe('AdminPage', () => {
+  it('renders admin dashboard title', () => {
+    render(<AdminPage />);
+
+    expect(screen.getByText('Admin Dashboard')).toBeInTheDocument();
+  });
+
+  it('renders description text', () => {
+    render(<AdminPage />);
+
+    expect(
+      screen.getByText('Manage users, organizations, and system settings')
+    ).toBeInTheDocument();
+  });
+
+  it('renders users management card', () => {
+    render(<AdminPage />);
+
+    expect(screen.getByText('Users')).toBeInTheDocument();
+    expect(
+      screen.getByText('Manage user accounts and permissions')
+    ).toBeInTheDocument();
+  });
+
+  it('renders organizations management card', () => {
+    render(<AdminPage />);
+
+    expect(screen.getByText('Organizations')).toBeInTheDocument();
+    expect(
+      screen.getByText('View and manage organizations')
+    ).toBeInTheDocument();
+  });
+
+  it('renders system settings card', () => {
+    render(<AdminPage />);
+
+    expect(screen.getByText('System')).toBeInTheDocument();
+    expect(
+      screen.getByText('System settings and configuration')
+    ).toBeInTheDocument();
+  });
+
+  it('displays coming soon messages', () => {
+    render(<AdminPage />);
+
+    const comingSoonMessages = screen.getAllByText('Coming soon...');
+    expect(comingSoonMessages).toHaveLength(3);
+  });
+
+  it('renders cards in grid layout', () => {
+    const { container } = render(<AdminPage />);
+
+    const grid = container.querySelector('.grid');
+    expect(grid).toBeInTheDocument();
+    expect(grid).toHaveClass('gap-4', 'md:grid-cols-2', 'lg:grid-cols-3');
+  });
+
+  it('renders with proper container structure', () => {
+    const { container } = render(<AdminPage />);
+
+    const containerDiv = container.querySelector('.container');
+    expect(containerDiv).toBeInTheDocument();
+    expect(containerDiv).toHaveClass('mx-auto', 'px-4', 'py-8');
+  });
+});