feat: rework to use next and host from single dockerfile

mta-sign-ui/next.config.js

@@ -1,13 +1,16 @@
 /** @type {import('next').NextConfig} */
 const nextConfig = {
+    output: 'export',
+    images: {
+        unoptimized: true,
+    },
+    // Rewrites only work during development (next dev)
+    // They are ignored during static export build
     rewrites: async () => {
         return [
             {
                 source: '/api/:path*',
-                destination:
-                    process.env.NODE_ENV === 'development'
-                        ? 'http://localhost:8000/api/:path*'
-                        : '/api/',
+                destination: 'http://localhost:8000/api/:path*',
             },
         ]
     },