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/robots.ts

@@ -4,11 +4,19 @@ export default function robots(): MetadataRoute.Robots {
   const siteUrl = process.env.NEXT_PUBLIC_SITE_URL || 'http://localhost:3000';
 
   return {
-    rules: {
-      userAgent: '*',
-      allow: '/',
-      disallow: ['/api/', '/_next/', '/admin/'],
-    },
+    rules: [
+      {
+        userAgent: '*',
+        allow: '/',
+        disallow: ['/api/', '/_next/', '/admin/'],
+      },
+      {
+        userAgent: ['GPTBot', 'ChatGPT-User', 'Google-Extended', 'Anthropic-ai', 'ClaudeBot', 'Claude-Web', 'PerplexityBot', 'Cohere-ai'],
+        allow: '/',
+        disallow: ['/api/', '/_next/', '/admin/'],
+      },
+    ],
     sitemap: `${siteUrl}/sitemap.xml`,
+    host: siteUrl,
   };
 }