feat: update AppRouter with layout routes, add Docs and Blog pages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/pages/DocDetailPage.tsx

@@ -0,0 +1,15 @@
+import { useParams } from 'react-router-dom';
+import SEOHead from '../components/seo/SEOHead';
+
+export default function DocDetailPage() {
+  const { slug } = useParams<{ slug: string }>();
+  return (
+    <>
+      <SEOHead title={slug ?? 'Doc'} description={`Documentation: ${slug}`} path={`/docs/${slug}`} />
+      <div className="max-w-4xl mx-auto py-16 px-6">
+        <h1 className="text-3xl font-bold text-gray-900 mb-4 capitalize">{slug?.replace(/-/g, ' ')}</h1>
+        <p className="text-gray-600">Content coming soon.</p>
+      </div>
+    </>
+  );
+}