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>

package.json

@@ -0,0 +1,25 @@
+{
+  "name": "garden-astro",
+  "version": "0.1.0",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "dev": "astro dev",
+    "build": "node scripts/copy-assets.mjs && astro build",
+    "preview": "astro preview"
+  },
+  "dependencies": {
+    "astro": "^5.0.0",
+    "github-slugger": "^2.0.0",
+    "katex": "^0.16.10",
+    "mermaid": "^11.0.0",
+    "rehype-katex": "^7.0.0",
+    "remark-math": "^6.0.0",
+    "unist-util-visit": "^5.0.0"
+  },
+  "allowScripts": {
+    "esbuild@0.27.7": true,
+    "esbuild@0.25.12": true,
+    "sharp@0.34.5": true
+  }
+}