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/src/pages/index.astro

@@ -0,0 +1,17 @@
+---
+
+---
+
+<html lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+		<link rel="icon" href="/favicon.ico" />
+		<meta name="viewport" content="width=device-width" />
+		<meta name="generator" content={Astro.generator} />
+		<title>Astro</title>
+	</head>
+	<body>
+		<h1>Astro</h1>
+	</body>
+</html>