feat: Add SEO/AEO/Geo improvements

- Add ai.txt and llms.txt endpoints for AI/LLM discoverability
- Enhance metadata across all pages (canonical URLs, OpenGraph, Twitter)
- Add structured data (JSON-LD) to blog index, tag pages
- Update robots.txt with AI crawler rules
- Improve BlogPosting and CollectionPage schemas

app/blog/page.tsx

@@ -1,26 +1,62 @@
+import { Link } from 'next-view-transitions';
 import { getAllPostsSorted } from '@/lib/posts';
 import { PostListWithControls } from '@/components/post-list-with-controls';
 import { TimelineWrapper } from '@/components/timeline-wrapper';
 import { SidebarLayout } from '@/components/sidebar-layout';
+import { SectionDivider } from '@/components/section-divider';
+import { ScrollReveal } from '@/components/scroll-reveal';
+import { FiTrendingUp } from 'react-icons/fi';
+import { siteConfig } from '@/lib/config';
+import { JsonLd } from '@/components/json-ld';
 
 export const metadata = {
-  title: '所有文章'
+  title: '所有文章',
+  description: '瀏覽所有文章，持續更新中。',
+  alternates: {
+    canonical: `${siteConfig.url}/blog`
+  }
 };
 
 export default function BlogIndexPage() {
   const posts = getAllPostsSorted();
 
+  // Blog schema
+  const blogSchema = {
+    '@context': 'https://schema.org',
+    '@type': 'Blog',
+    name: '所有文章',
+    description: '瀏覽所有文章，持續更新中。',
+    url: `${siteConfig.url}/blog`,
+    inLanguage: siteConfig.defaultLocale,
+    blogPost: posts.slice(0, 10).map((post) => ({
+      '@type': 'BlogPosting',
+      headline: post.title,
+      url: `${siteConfig.url}${post.url}`,
+      datePublished: post.published_at,
+      dateModified: post.updated_at || post.published_at,
+      author: {
+        '@type': 'Person',
+        name: siteConfig.author
+      }
+    }))
+  };
+
   return (
     <section className="space-y-4">
+      <JsonLd data={blogSchema} />
       <SidebarLayout>
-        <header className="space-y-1">
-          <h1 className="type-title font-semibold text-slate-900 dark:text-slate-50">
-            所有文章
-          </h1>
-          <p className="type-small text-slate-500 dark:text-slate-400">
-            繼續往下滑，慢慢逛逛。
-          </p>
-        </header>
+        <SectionDivider>
+          <ScrollReveal>
+            <header className="space-y-1">
+              <h1 className="type-title font-semibold text-slate-900 dark:text-slate-50">
+                所有文章
+              </h1>
+              <p className="type-small text-slate-500 dark:text-slate-400">
+                繼續往下滑，慢慢逛逛。
+              </p>
+            </header>
+          </ScrollReveal>
+        </SectionDivider>
         <PostListWithControls posts={posts} />
       </SidebarLayout>
     </section>