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>

.gitignore

@@ -0,0 +1,4 @@
+node_modules/
+dist/
+.astro/
+public/assets/