Extend llms.txt to all content types; fix a gitignore bug

scripts/generate-llms.astro-site.mjs covers writings, portfolio,
bookshelf, and blogs (unblocked now that site.config.ts exists from
the feeds/meta work), wired into apps/site's build script.

Also fixes .gitignore: the bare `public` pattern (meant to ignore the
Zola build's root-level output directory) was matching at any depth,
so apps/site/public/ and apps/cms/public/ were being silently
excluded from every commit despite `git add` reporting them as
staged for directory adds (the ignore-file warning only surfaces for
an explicitly named path, not a recursive directory add — easy to
miss). Scoped to `/public` so only the root output dir is ignored.
Picks up robots.txt, the Astro scaffold's favicon, llms.txt, and
Strapi's own public/robots.txt, none of which were actually tracked
until now.

apps/site/package.json

@@ -7,7 +7,8 @@
   },
   "scripts": {
     "dev": "astro dev",
-    "build": "astro build && pagefind --site dist",
+    "generate:llms": "node ../../scripts/generate-llms.astro-site.mjs",
+    "build": "pnpm run generate:llms && astro build && pagefind --site dist",
     "preview": "astro preview",
     "check": "astro check",
     "astro": "astro"