feat: implement logout functionality in Layout component and enhance AuthContext with auto-logout feature

frontend/src/components/__tests__/Layout.test.tsx

@@ -1,10 +1,17 @@
 import { ReactNode } from 'react'
-import { describe, it, expect } from 'vitest'
+import { describe, it, expect, vi } from 'vitest'
 import { render, screen } from '@testing-library/react'
 import { BrowserRouter } from 'react-router-dom'
 import Layout from '../Layout'
 import { ThemeProvider } from '../../context/ThemeContext'
 
+// Mock AuthContext
+vi.mock('../../context/AuthContext', () => ({
+  useAuth: () => ({
+    logout: vi.fn(),
+  }),
+}))
+
 const renderWithProviders = (children: ReactNode) => {
   return render(
     <BrowserRouter>