feat: 接入预览模式（Next.js Draft Mode）

app/cases/[slug]/page.tsx

@@ -1,7 +1,9 @@
 import { notFound } from "next/navigation";
 import type { Metadata } from "next";
 import { getCaseStudyBySlug } from "@/services/case.service";
+import { getPreviewOrFallback } from "@/services/preview.service";
 import { BlockRenderer } from "@/blocks/BlockRenderer";
+import type { CaseStudyPageDetail } from "@/types/wagtail";
 
 interface CaseStudyDetailPageProps {
   params: Promise<{ slug: string }>;
@@ -19,7 +21,11 @@ export default async function CaseStudyDetailPage({
   params,
 }: CaseStudyDetailPageProps) {
   const { slug } = await params;
-  const item = await getCaseStudyBySlug(slug).catch(() => null);
+  const item = await getPreviewOrFallback<CaseStudyPageDetail>(
+    "cases.casestudypage",
+    "body,client_name,industry,published_at,summary",
+    () => getCaseStudyBySlug(slug).catch(() => null),
+  );
 
   if (!item) {
     notFound();