Add homework review link to admin sidebar

- Admin sidebar now has "ДЗ на проверку" link → /curator/homework
- Curator layout renders children-only for admin (no double sidebar)
- Active state highlights correctly when on /curator/* routes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/curator/layout.tsx

@@ -9,6 +9,11 @@ export default async function CuratorLayout({ children }: { children: React.Reac
   if (!session) redirect("/login");
   if (session.user.role !== "curator" && session.user.role !== "admin") redirect("/dashboard");
 
+  // Admin uses their own layout — render content only
+  if (session.user.role === "admin") {
+    return <>{children}</>;
+  }
+
   return (
     <div className="min-h-screen flex" style={{ backgroundColor: "var(--background)" }}>
       {/* Sidebar */}