Add backend-generated sitemap with website manifest sync and nginx SEO proxy support.

Stores synced route config from /meshkee/sitemap-config.json, serves sitemap.xml and robots.txt per tenant, and invalidates cache on CMS writes.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/websites-agent/README.md

@@ -9,6 +9,9 @@
 #   POST /ssl        { host, slug? }             — certbot for apex + www (nginx must exist)
 #   GET  /health
 #
+# Scripts on the VM (same folder):
+#   patch-nginx-seo.sh <host>  — add /sitemap.xml + /robots.txt API proxies to an existing nginx site
+#
 # Env (.env): PORT, DEPLOY_TOKEN, ALLOWED_SLUGS
 #
 # Note: provision.sh intentionally skips certbot. SSL is issued via POST /ssl so