feat: sitemap-aware batch conflict and the sitemap_blocked issue

- noindex_published fires only when a sitemap file lists the address now
  (read once per batch through contract.Listing)
- CMS issue sitemap_blocked (severity error, tool seo_update_robots,
  details line and rule): a listed address the production robots.txt
  keeps Googlebot from
- the SEO tab's P1 shows status.excluded_title with the reason (noindex,
  canonical elsewhere, redirect, or the type switched off in the sitemap
  settings via ListingSettings.TypesOff) as a plain callout
- robots.txt is composed once per check of many addresses

batch_test.go

@@ -70,6 +70,8 @@ func TestBatch(t *testing.T) {
 	token := env.admin(t, true)
 	env.createPage(t, token, map[string]any{"title": "Page A", "slug": "a", "excerpt": "About A", "published": true})
 	env.createPage(t, token, map[string]any{"title": "Page B", "slug": "b", "excerpt": "About B", "published": true})
+	// noindex_published needs the address in a sitemap file.
+	env.rebuildSitemap(t)
 	agent := env.principal(t, env.admin(t, false, "golem15.seo.manage"))
 
 	changes := []any{