SEO prerender pipeline + register AI routes and tighten CSP

- Static prerender + sitemap/robots for marketing, blog, and tool pages
  (entry-server, Seo component, prerender/sitemap scripts, NotFoundPage)
- Register aiRoutes and extend CSP for Turnstile + Spaces image hosts

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/web/src/pages/blog/BlogPostPage.tsx

@@ -39,7 +39,7 @@ export default function BlogPostPage() {
           <div className="mt-6 flex items-center gap-3 text-sm text-ink-500">
             <span>{post.author}</span>
             <span className="text-ink-300">·</span>
-            <span>{formatDate(post.publishedAt)}</span>
+            <time dateTime={post.publishedAt}>{formatDate(post.publishedAt)}</time>
             <span className="text-ink-300">·</span>
             <span className="inline-flex items-center gap-1.5">
               <Clock className="h-3.5 w-3.5" />