Add robots.txt SSR route and sitemap link tag for SEO discovery

The static public/robots.txt wasn't being served because all requests
route through the Worker → React Router pipeline. Adding an explicit
SSR route (matching the existing sitemap.xml pattern) ensures robots.txt
is always served. Also adds a <link rel="sitemap"> tag as a secondary
discovery path for crawlers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bchapuis

apps/www/src/root.tsx

@@ -13,6 +13,7 @@ export const links = () => [
   { rel: "preload", href: stylesheet, as: "style" },
   { rel: "stylesheet", href: stylesheet },
   { rel: "icon", href: "/icon.svg", type: "image/svg+xml" },
+  { rel: "sitemap", type: "application/xml", href: "/sitemap.xml" },
 ];
 
 export function Layout({ children }: { children: React.ReactNode }) {

apps/www/src/routes.ts

@@ -5,6 +5,7 @@ export default [
   route("terms", "routes/terms.tsx"),
   route("privacy", "routes/privacy.tsx"),
   route("cookies", "routes/cookies.tsx"),
+  route("robots.txt", "routes/robots[.]txt.tsx"),
   route("sitemap.xml", "routes/sitemap[.]xml.tsx"),
   route("nodes", "routes/nodes/index.tsx"),
   route("nodes/:category", "routes/nodes/$category.tsx"),

apps/www/src/routes/robots[.]txt.tsx

@@ -0,0 +1,16 @@
+const websiteUrl = import.meta.env.VITE_WEBSITE_URL;
+
+export function loader() {
+  const body = `User-agent: *
+Allow: /
+
+Sitemap: ${websiteUrl}/sitemap.xml
+`;
+
+  return new Response(body, {
+    headers: {
+      "Content-Type": "text/plain",
+      "Cache-Control": "public, max-age=86400",
+    },
+  });
+}