🚚(frontend) rename folder app to apps

The folder app will be used for more than one app, so it was
renamed to apps.

src/frontend/apps/desk/next.config.js

@@ -0,0 +1,14 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  trailingSlash: true,
+  async rewrites() {
+    return [
+      {
+        source: '/api/:slug*/',
+        destination: `${process.env.NEXT_PUBLIC_API_URL}:slug*/`, // Matched parameters can be used in the destination
+      },
+    ];
+  },
+};
+
+module.exports = nextConfig;