feat: add ssr route for testing

Author: orinokai

demos/nx-next-monorepo-demo/apps/demo-monorepo/pages/api/index.js

@@ -0,0 +1,7 @@
+// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
+
+export default function handler(req, res) {
+  res.status(200).json({
+    body: 'Hello world',
+  });
+}