feat: 接入预览模式（Next.js Draft Mode）

app/blog/[slug]/page.tsx

@@ -1,7 +1,9 @@
 import { notFound } from "next/navigation";
 import type { Metadata } from "next";
 import { getBlogBySlug } from "@/services/blog.service";
+import { getPreviewOrFallback } from "@/services/preview.service";
 import { BlockRenderer } from "@/blocks/BlockRenderer";
+import type { BlogPageDetail } from "@/types/wagtail";
 
 interface BlogDetailPageProps {
   params: Promise<{ slug: string }>;
@@ -17,7 +19,11 @@ export async function generateMetadata({
 
 export default async function BlogDetailPage({ params }: BlogDetailPageProps) {
   const { slug } = await params;
-  const post = await getBlogBySlug(slug).catch(() => null);
+  const post = await getPreviewOrFallback<BlogPageDetail>(
+    "blog.blogpage",
+    "body,intro,published_at",
+    () => getBlogBySlug(slug).catch(() => null),
+  );
 
   if (!post) {
     notFound();