feat(problems): add published check in problem layout

src/app/(app)/problems/[problemId]/layout.tsx

@@ -1,3 +1,4 @@
+import prisma from "@/lib/prisma";
 import { notFound } from "next/navigation";
 import { ProblemHeader } from "@/features/problems/components/header";
 
@@ -13,6 +14,19 @@ const Layout = async ({ children, params }: LayoutProps) => {
     return notFound();
   }
 
+  const problem = await prisma.problem.findUnique({
+    select: {
+      isPublished: true,
+    },
+    where: {
+      id: problemId,
+    },
+  });
+
+  if (!problem?.isPublished) {
+    return notFound();
+  }
+
   return (
     <div className="flex flex-col h-screen">
       <ProblemHeader />