feat: add blog with archives, pagination, search, sharing and RSS

- Content collection (one folder per post) with zod schema
- /blog, category and tag archives with /sayfa/<n>/ pagination
- Post page: breadcrumbs, date badges, share bar, TOC, DIY notice,
  code copy, license line, prev/next, BlogPosting + BreadcrumbList JSON-LD
- Sidebar: Pagefind search, categories, featured fallback, tag cloud
- Sätteri HAST plugins for figure/figcaption and external links
- Dual-theme Shiki, themed prose, RSS feed, latest posts on home
- Three sample posts marked as examples

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/blog/ShareBar.astro

@@ -0,0 +1,82 @@
+---
+import { Icon } from 'astro-icon/components';
+import { blog, site } from '../../lib/data';
+
+export interface Props {
+  url: string;
+  title: string;
+}
+
+const { url, title } = Astro.props;
+const fill = (tpl: string) =>
+  tpl.replace('{url}', encodeURIComponent(url)).replace('{title}', encodeURIComponent(title));
+const btn =
+  'border-line hover:border-fg hover:bg-fg hover:text-bg inline-flex size-11 cursor-pointer items-center justify-center border transition-colors';
+---
+
+<div data-share data-url={url} data-title={title} data-copied={blog.post.copied}>
+  <p class="font-display mb-3 text-sm font-bold tracking-wide uppercase" id="share-label">
+    {blog.post.shareLabel}
+  </p>
+  <ul class="flex flex-wrap gap-2" aria-labelledby="share-label">
+    {blog.share.map((s) => (
+      <li>
+        <a
+          href={fill(s.url)}
+          target={s.id === 'email' ? undefined : '_blank'}
+          rel={s.id === 'email' ? undefined : 'noopener noreferrer'}
+          title={s.label}
+          class={btn}
+        >
+          <Icon name={s.icon} class="size-5" aria-hidden="true" />
+          <span class="sr-only">
+            {s.label}
+            {s.id !== 'email' && ` ${site.ui.newTab}`}
+          </span>
+        </a>
+      </li>
+    ))}
+    <li>
+      <button type="button" data-share-copy title={blog.post.copyLink} class={btn}>
+        <Icon name="tabler:link" class="size-5" aria-hidden="true" />
+        <span class="sr-only">{blog.post.copyLink}</span>
+      </button>
+    </li>
+    <li hidden data-share-native-item>
+      <button type="button" data-share-native title={blog.post.nativeShare} class={btn}>
+        <Icon name="tabler:share" class="size-5" aria-hidden="true" />
+        <span class="sr-only">{blog.post.nativeShare}</span>
+      </button>
+    </li>
+  </ul>
+  <p
+    data-share-status
+    role="status"
+    aria-live="polite"
+    class="text-accent-text mt-2 min-h-5 text-sm font-semibold"
+  ></p>
+</div>
+
+<script>
+  for (const root of document.querySelectorAll<HTMLElement>('[data-share]')) {
+    const { url = location.href, title = document.title, copied = '' } = root.dataset;
+    const status = root.querySelector<HTMLElement>('[data-share-status]')!;
+
+    root.querySelector('[data-share-copy]')?.addEventListener('click', async () => {
+      try {
+        await navigator.clipboard.writeText(url);
+        status.textContent = copied;
+        setTimeout(() => (status.textContent = ''), 2500);
+      } catch {
+        prompt('', url);
+      }
+    });
+
+    if (typeof navigator.share === 'function') {
+      root.querySelector<HTMLElement>('[data-share-native-item]')!.hidden = false;
+      root.querySelector('[data-share-native]')!.addEventListener('click', () => {
+        navigator.share({ url, title }).catch(() => {});
+      });
+    }
+  }
+</script>