Add prisma setup for example.

examples/blog-engine/prisma/schema.prisma

@@ -0,0 +1,18 @@
+generator client {
+        provider      = "prisma-client-js"
+        binaryTargets = ["native", "rhel-openssl-1.0.x"]
+}
+
+datasource db {
+        provider = "postgresql"
+        url      = env("BLOG_DATABASE_URL")
+}
+
+model Post {
+        title String
+        slug  String @id
+        body  String
+
+        createdAt DateTime @default(now())
+        updatedAt DateTime @updatedAt
+}

examples/blog-engine/prisma/seed.mjs

@@ -0,0 +1,22 @@
+import { PrismaClient } from "@prisma/client";
+const prisma = new PrismaClient();
+
+const posts = [
+  {
+    slug: "elm-pages demo",
+    title: "Is elm-pages Full-Stack?",
+    body: `
+# Is elm-pages Full-Stack?
+
+Yes it is!
+    `.trim(),
+  },
+];
+
+posts.forEach(async (post) => {
+  await prisma.post.upsert({
+    where: { slug: post.slug },
+    update: post,
+    create: post,
+  });
+});