Scaffold Apollo backend domain API

src/context.js

@@ -0,0 +1,10 @@
+import { prisma } from './prisma-client.js';
+
+export async function buildContext(req) {
+  const userId = req.headers['x-user-id'];
+  const user = userId
+    ? await prisma.user.findUnique({ where: { id: String(userId) } })
+    : null;
+
+  return { prisma, user };
+}