feat: add gated housekeeping foundation preview

src/app/admin-next/layout.tsx

@@ -0,0 +1,17 @@
+import { notFound } from "next/navigation";
+import type { ReactNode } from "react";
+import { env } from "@/env";
+import { isHousekeepingPreviewEnabled } from "@/features/housekeeping/foundation/preview-gate";
+
+export default function AdminNextLayout({ children }: { children: ReactNode }) {
+	if (
+		!isHousekeepingPreviewEnabled({
+			nodeEnv: env.NODE_ENV,
+			flag: env.HOUSEKEEPING_NEXT_PREVIEW_ENABLED,
+		})
+	) {
+		notFound();
+	}
+
+	return children;
+}