init: project setup

src/pages/robots.txt.ts

@@ -0,0 +1,13 @@
+import type { APIRoute } from 'astro'
+
+const getRobotsTxt = (sitemapURL: URL) => `
+User-agent: *
+Allow: /
+
+Sitemap: ${sitemapURL.href}
+`
+
+export const GET: APIRoute = ({ site }) => {
+  const sitemapURL = new URL('sitemap-index.xml', site)
+  return new Response(getRobotsTxt(sitemapURL))
+}