feat: add md index page with category grouping

apps/blog/src/pages/md/index.astro

@@ -0,0 +1,42 @@
+---
+import { getCollection } from 'astro:content';
+import Layout from '../../layouts/Layout.astro';
+
+const posts = await getCollection('posts');
+
+// Group by category (default: "posts")
+const grouped = posts.reduce((acc, post) => {
+  const category = post.data.category ?? 'posts';
+  if (!acc[category]) acc[category] = [];
+  acc[category].push(post);
+  return acc;
+}, {} as Record<string, typeof posts>);
+
+// Sort categories alphabetically
+const sortedCategories = Object.keys(grouped).sort();
+
+// Sort posts within each category: pinned first, then by date descending
+for (const category of sortedCategories) {
+  grouped[category].sort((a, b) => {
+    if (a.data.pinned && !b.data.pinned) return -1;
+    if (!a.data.pinned && b.data.pinned) return 1;
+    return b.data.date.getTime() - a.data.date.getTime();
+  });
+}
+
+function formatDate(date: Date): string {
+  const d = String(date.getDate()).padStart(2, '0');
+  const m = String(date.getMonth() + 1).padStart(2, '0');
+  const y = String(date.getFullYear()).slice(-2);
+  return `${d}/${m}/${y}`;
+}
+---
+<Layout title="md - lewis m.w.">
+
+{sortedCategories.map(category => (
+<details open>
+  <summary>{category}</summary>
+<pre set:html={grouped[category].map(post => `<span class="muted">${formatDate(post.data.date)}</span>    <a href="/md/${post.id}">${post.data.title}</a>${post.data.pinned ? ' [pinned]' : ''}`).join('\n')} />
+</details>
+))}
+</Layout>