site: add llms.txt index pointing at markdown blog siblings

Author: rgbkrk

app/llms.txt/route.ts

@@ -0,0 +1,29 @@
+import { getAllPosts } from "@/lib/blog";
+import { absoluteUrl, siteConfig } from "@/lib/site";
+
+export const dynamic = "force-static";
+
+export async function GET() {
+  const posts = await getAllPosts();
+
+  const lines = [
+    `# ${siteConfig.name}`,
+    "",
+    `> ${siteConfig.description}`,
+    "",
+    "## Blog",
+    "",
+    ...posts.map(
+      (post) =>
+        `- [${post.title}](${absoluteUrl(`/blog/${post.slug}/index.md`)}): ${post.description}`,
+    ),
+    "",
+  ];
+
+  return new Response(lines.join("\n"), {
+    headers: {
+      "Content-Type": "text/plain; charset=utf-8",
+      "Cache-Control": "public, s-maxage=3600, stale-while-revalidate=86400",
+    },
+  });
+}