seo: localize blog metadata and FAQ, expand llms.txt, guard blog facts in tests

Open Graph locale, JSON-LD language and the blog breadcrumb follow the
post's language, the FAQ heading is translated, and time elements use
ISO dates. llms.txt and llms-full.txt list core capabilities next to the
licensing and deployment boundaries. New tests keep FAQ answers plain
text and in step with the English, catch repeated paragraphs, overlong
meta descriptions and "prorated" upgrade wording, and a build verifier
checks the rendered blog. IndexNow no longer reports success when a
sitemap cannot be read.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/indexnow.mjs

@@ -47,9 +47,22 @@ if (live?.trim() !== key) {
   process.exit(1);
 }
 
+// Sitemaps that could not be read. An error page must not pass for an empty
+// sitemap: that would skip its URLs and still report success.
+const failed = [];
+
 /** Every <loc> under a sitemap, following sitemap indexes. */
 async function urlsOf(sitemap) {
-  const xml = await fetch(sitemap).then((r) => r.text());
+  let xml;
+  try {
+    const res = await fetch(sitemap);
+    if (!res.ok) throw new Error(`HTTP ${res.status}`);
+    xml = await res.text();
+    if (!/<(urlset|sitemapindex)[\s>]/.test(xml)) throw new Error("not a sitemap");
+  } catch (err) {
+    failed.push(`${sitemap}: ${err.message}`);
+    return [];
+  }
   const locs = [...xml.matchAll(/<loc>\s*([^<\s]+)\s*<\/loc>/g)].map((m) => m[1]);
   if (!/<sitemapindex/.test(xml)) return locs;
   // One at a time: a burst of parallel fetches trips Cloudflare's timeouts.
@@ -62,6 +75,11 @@ const sources = which === "all" ? Object.values(SITEMAPS) : [SITEMAPS[which]];
 const found = [];
 for (const s of sources) found.push(...(await urlsOf(s)));
 const urlList = [...new Set(found)].filter((u) => u.startsWith(`${ORIGIN}/`));
+for (const f of failed) console.error(`[indexnow] could not read ${f}`);
+if (!urlList.length) {
+  console.error("[indexnow] no URLs found, nothing submitted");
+  process.exit(1);
+}
 
 // One request takes up to 10,000 URLs.
 for (let i = 0; i < urlList.length; i += 10000) {
@@ -75,3 +93,5 @@ for (let i = 0; i < urlList.length; i += 10000) {
   console.log(`[indexnow] ${batch.length} URLs (${which}) submitted: HTTP ${res.status}`);
   if (!res.ok) process.exit(1);
 }
+// The readable sitemaps went in above; an unreadable one still fails the run.
+if (failed.length) process.exit(1);