feat: rewrite to Next.js v13 app directory

Improvements:
- Hide switch theme input (ugly little white square)
- i18n without subpath (e.g: /fr or /en), same url whatever the locale used

components/Footer/index.tsx

@@ -0,0 +1,14 @@
+import { FooterText } from './FooterText'
+import { FooterVersion } from './FooterVersion'
+
+export const Footer = async (): Promise<JSX.Element> => {
+  const { readPackage } = await import('read-pkg')
+  const { version } = await readPackage()
+
+  return (
+    <footer className='flex flex-col items-center justify-center border-t-2 border-gray-600 bg-white py-6 text-lg dark:border-gray-400 dark:bg-black'>
+      <FooterText />
+      <FooterVersion version={version} />
+    </footer>
+  )
+}