Scaffold Astro/Strapi monorepo for the site rebuild

Set up a pnpm workspace with apps/site (Astro) and apps/cms (Strapi,
SQLite-backed) as the foundation for the new digital-legacy site.
Switches package management to pnpm and adds Biome for linting/
formatting, replacing npm/no-linter setup. Existing Zola site stays
in place for now and will be migrated/removed progressively.

apps/site/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "site",
+  "type": "module",
+  "version": "0.0.1",
+  "engines": {
+    "node": ">=22.12.0"
+  },
+  "scripts": {
+    "dev": "astro dev",
+    "build": "astro build",
+    "preview": "astro preview",
+    "astro": "astro"
+  },
+  "dependencies": {
+    "astro": "^7.2.9"
+  },
+  "allowScripts": {
+    "esbuild": true
+  }
+}