Add PPR (#745)

* Update to next v15, switch to pnpm

* Delete package-lock.json

* Add PPR

* Update to next@canary

* Update starter-example to next@canary

* Update file extension

* Update ts compiler options to match CNA

* Fix ts errors

dashboard/final-example/next.config.mjs

@@ -0,0 +1,9 @@
+/** @type {import('next').NextConfig} */
+
+const nextConfig = {
+  experimental: {
+    ppr: 'incremental',
+  },
+};
+
+export default nextConfig;