feat: add feature UI components with useQuery hooks

- navigation: SiteHeader component + useHeader hook
- blog: ArticleCard, ArticleList, ArticleDetail + useArticleList,
  useArticleBySlug hooks
- marketing-pages: PageHero, PageContent + usePageBySlug,
  useSiteSettings hooks
- App pages now thin server wrappers that prefetch + hydrate;
  feature components own their data fetching via useSuspenseQuery

packages/blog/src/ui/components/article-card.tsx

@@ -0,0 +1,23 @@
+import type { Article } from "../../entities/models/article";
+
+export type ArticleCardProps = {
+  article: Article;
+};
+
+export function ArticleCard({ article }: ArticleCardProps) {
+  return (
+    <article className="rounded-lg border border-border bg-card p-4 transition-colors hover:bg-accent/50">
+      <a href={`/blog/${article.slug}`}>
+        <h3 className="text-lg font-semibold text-card-foreground">
+          {article.title}
+        </h3>
+      </a>
+      <time
+        className="text-sm text-muted-foreground"
+        dateTime={article.createdAt.toISOString()}
+      >
+        {article.createdAt.toLocaleDateString()}
+      </time>
+    </article>
+  );
+}