fix(manifest-ui): add missing post-detail block definition

The Post Detail link in the sidebar was 404ing because the block
was registered in registry.json but missing from the categories
array in the dynamic page handler. Added block definition with
fullscreen and inline variants.

Author: claude

packages/manifest-ui/app/blocks/[category]/[block]/page.tsx

@@ -943,6 +943,114 @@ const categories: Category[] = [
   actions={{
     onReadMore: (post) => console.log("Read more:", post.title)
   }}
+/>`
+          }
+        ]
+      },
+      {
+        id: 'post-detail',
+        name: 'Post Detail',
+        description:
+          'Full post view with Medium-style typography, cover image, author info, content, and related posts.',
+        registryName: 'post-detail',
+        layouts: ['inline', 'fullscreen'],
+        actionCount: 2,
+        variants: [
+          {
+            id: 'fullscreen',
+            name: 'Fullscreen',
+            component: (
+              <PostDetail appearance={{ displayMode: 'fullscreen' }} />
+            ),
+            usageCode: `<PostDetail
+  data={{
+    post: {
+      title: "Getting Started with Agentic UI Components",
+      excerpt: "Learn how to build conversational interfaces with our comprehensive component library designed for AI-powered applications.",
+      coverImage: "https://images.unsplash.com/photo-1633356122544-f134324a6cee?w=800",
+      author: {
+        name: "Sarah Chen",
+        avatar: "https://i.pravatar.cc/150?u=sarah"
+      },
+      publishedAt: "2024-01-15",
+      readTime: "5 min read",
+      tags: ["Tutorial", "Components", "AI", "React", "TypeScript"],
+      category: "Tutorial"
+    },
+    content: \`
+      <p>Building modern AI-powered applications requires a new approach to UI design. Traditional web components don't always translate well to conversational interfaces, where context and flow are paramount.</p>
+
+      <p>Our Agentic UI component library provides a collection of purpose-built components that work seamlessly within chat interfaces. From payment flows to product displays, each component is designed with the unique constraints of conversational UIs in mind.</p>
+
+      <h2>Key Features</h2>
+      <p>Each component supports three display modes: inline (within the chat flow), fullscreen (for complex interactions), and picture-in-picture (persistent visibility). This flexibility allows you to create rich, interactive experiences without breaking the conversational flow.</p>
+
+      <p>Components are designed mobile-first and touch-friendly, ensuring a great experience across all devices. They automatically adapt to light and dark themes, and integrate seamlessly with MCP tools for backend communication.</p>
+    \`,
+    relatedPosts: [
+      {
+        title: "Designing for Conversational Interfaces",
+        excerpt: "Best practices for creating intuitive UI components that work within chat environments.",
+        coverImage: "https://images.unsplash.com/photo-1559028012-481c04fa702d?w=800",
+        author: { name: "Alex Rivera", avatar: "https://i.pravatar.cc/150?u=alex" },
+        publishedAt: "2024-01-12",
+        readTime: "8 min read",
+        tags: ["Design", "UX"],
+        category: "Design",
+        url: "https://example.com/posts/designing-conversational-interfaces"
+      },
+      {
+        title: "MCP Integration Patterns",
+        excerpt: "How to leverage Model Context Protocol for seamless backend communication.",
+        coverImage: "https://images.unsplash.com/photo-1558494949-ef010cbdcc31?w=800",
+        author: { name: "Jordan Kim", avatar: "https://i.pravatar.cc/150?u=jordan" },
+        publishedAt: "2024-01-10",
+        readTime: "12 min read",
+        tags: ["MCP", "Backend"],
+        category: "Development",
+        url: "https://example.com/posts/mcp-integration-patterns"
+      }
+    ]
+  }}
+  appearance={{
+    showCover: true,
+    showAuthor: true,
+    displayMode: "fullscreen"
+  }}
+  actions={{
+    onBack: () => console.log("Back clicked"),
+    onReadRelated: (post) => console.log("Read related:", post.title)
+  }}
+/>`
+          },
+          {
+            id: 'inline',
+            name: 'Inline',
+            component: <PostDetail appearance={{ displayMode: 'inline' }} />,
+            usageCode: `<PostDetail
+  data={{
+    post: {
+      title: "Getting Started with Agentic UI Components",
+      excerpt: "Learn how to build conversational interfaces with our comprehensive component library.",
+      coverImage: "https://images.unsplash.com/photo-1633356122544-f134324a6cee?w=800",
+      author: {
+        name: "Sarah Chen",
+        avatar: "https://i.pravatar.cc/150?u=sarah"
+      },
+      publishedAt: "2024-01-15",
+      readTime: "5 min read",
+      tags: ["Tutorial", "Components"],
+      category: "Tutorial"
+    },
+    content: "<p>Building modern AI-powered applications requires a new approach...</p>"
+  }}
+  appearance={{
+    showCover: true,
+    displayMode: "inline"
+  }}
+  actions={{
+    onReadMore: () => console.log("Read more clicked")
+  }}
 />`
           }
         ]