fix(website): SEO canonicals, host redirects, sitemap, app noindex

Addresses the high-volume issues from the Ahrefs audit:
- Worker entrypoint 301s every request not on https://paseo.sh
  (www subdomain and http variants), killing the duplicate-page
  errors and the HTTP→HTTPS internal-link notices.
- pageMeta() emits <link rel="canonical"> and og:url per route;
  every head() call now passes its canonical path.
- /blog stops rewriting itself to /blog?drafts=false; the search
  param only appears when explicitly true.
- Sitemap includes /blog and each post.
- Trim homepage title under SERP truncation, rewrite /agents meta
  description under 160 chars, pad short descriptions on
  /privacy, /download, /cloud, /changelog, /docs.
- app.paseo.sh gets <meta robots=noindex,nofollow> and a
  Disallow-all robots.txt so the SPA shell stops polluting the
  crawl with H1-missing / no-OG / low-word-count warnings.

packages/website/src/components/agent-route.tsx

@@ -5,7 +5,7 @@ import { pageMeta } from "~/meta";
 export function agentRouteOptions(slug: string) {
   const page = getAgentPage(slug);
   return {
-    head: () => ({ meta: pageMeta(page.metaTitle, page.metaDescription) }),
+    head: () => pageMeta(page.metaTitle, page.metaDescription, `/${slug}`),
     component: function AgentLandingPage() {
       return <LandingPage title={page.title} subtitle={page.subtitle} />;
     },