refactor: reorganize layout structure by moving Header and Footer components to RootLayout

apps/landing/src/app/(frontend)/layout.tsx

@@ -1,6 +1,8 @@
 import { type Metadata } from 'next';
 import { Inter } from 'next/font/google';
 import '../../styles/globals.css';
+import Footer from './_components/footer';
+import { Header } from './_components/header';
 import { ThemeProvider } from './_components/theme-provider';
 
 const inter = Inter({ subsets: ['latin'] });
@@ -24,7 +26,11 @@ export default function RootLayout({
           enableSystem
           disableTransitionOnChange
         >
-          {children}
+          <div className="flex min-h-screen flex-col">
+            <Header />
+            <main className="flex-1">{children}</main>
+            <Footer />
+          </div>
         </ThemeProvider>
       </body>
     </html>