Astro garden skeleton: Quartz-compatible URLs, Obsidian markdown, odometer homepage

- glob content loader over the vault's Digital_Garden with verbatim-path ids
- remark plugin: wikilinks, image embeds (wiki + relative md), callouts
- URL parity with live Quartz sitemap verified 102/102 (built set is a
  strict superset: +30 synthetic folder listings)
- KaTeX, lazy mermaid, shiki dual themes, quoted-string draft handling
- copy-assets resolves embeds vault-wide (fixes live-site 404s for
  Blog Scratch/assets images) into flat /assets/
- homepage odometer widget: fetches api.c0smere.net baseline, ticks at
  lifetime average rate, fail-closed hidden on error
- deploy/: nginx try_files config + compose (port 18100) + containerized
  build script for cyrion

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/pages/[...slug].astro

@@ -0,0 +1,79 @@
+---
+import { getCollection, render } from 'astro:content';
+import Base from '../layouts/Base.astro';
+import { slugForId, urlForId } from '../lib/quartz-compat.mjs';
+
+export async function getStaticPaths() {
+  const entries = await getCollection('garden', (e) => !e.data.draft);
+  const ids = new Set(entries.map((e) => e.id));
+
+  const paths = entries
+    .filter((e) => e.id !== 'index')
+    .map((e) => ({
+      params: { slug: slugForId(e.id) },
+      props: { entry: e, listing: null },
+    }));
+
+  // synthetic listing pages for folders that have no index.md
+  const folders = new Set<string>();
+  for (const id of ids) {
+    let d = id.includes('/') ? id.slice(0, id.lastIndexOf('/')) : '';
+    while (d) {
+      folders.add(d);
+      d = d.includes('/') ? d.slice(0, d.lastIndexOf('/')) : '';
+    }
+  }
+  for (const folder of folders) {
+    if (ids.has(`${folder}/index`)) continue;
+    const children = entries
+      .filter((e) => {
+        const dir = e.id.includes('/') ? e.id.slice(0, e.id.lastIndexOf('/')) : '';
+        return dir === folder && !e.id.endsWith('/index');
+      })
+      .map((e) => ({
+        title: e.data.title ?? e.id.split('/').pop(),
+        url: urlForId(e.id),
+      }));
+    const subfolders = [...folders]
+      .filter((f) => {
+        const dir = f.includes('/') ? f.slice(0, f.lastIndexOf('/')) : '';
+        return dir === folder;
+      })
+      .map((f) => ({
+        title: f.split('/').pop(),
+        url: '/' + slugForId(f) + '/',
+      }));
+    paths.push({
+      params: { slug: slugForId(folder) + '/index' },
+      props: {
+        entry: null,
+        listing: { name: folder.split('/').pop(), items: [...subfolders, ...children] },
+      },
+    });
+  }
+
+  return paths;
+}
+
+const { entry, listing } = Astro.props;
+const title = entry
+  ? (entry.data.title ?? entry.id.split('/').pop())
+  : listing.name;
+const Content = entry ? (await render(entry)).Content : null;
+---
+
+<Base title={title} description={entry?.data.description}>
+  <h1>{title}</h1>
+  {Content && <Content />}
+  {
+    listing && (
+      <ul>
+        {listing.items.map((item) => (
+          <li>
+            <a href={item.url}>{item.title}</a>
+          </li>
+        ))}
+      </ul>
+    )
+  }
+</Base>