feat: page registry with its admin screen and signpost type

- golem15_seo_pages (migration 202610280002): the site's own frontend pages
  with an address and a name per locale, kind, origin, parent, content date
  and note; settings routes_reported_at
- SEO > Pages (golem15.seo.pages) after URL rules: list with kind, origin
  and missing filters and the missing row state, form with the P9 partial;
  the plugin's form extension saves the address and name per locale and
  refuses url_required, url_invalid, url_taken and url_owned
- menu item type seo-page with a content descriptor, so each page gets
  the SEO tab, resolves ok and is listed in the sitemaps grouped by kind
  (pages, offers, services, landing-pages, titled per locale)
- management API GET/POST /_seo/api/v1/pages, PUT/DELETE /pages/{id} and
  the MCP tools seo_list_pages, seo_create_page, seo_update_page,
  seo_delete_page (in this commit because the operations parity test maps
  every Pages operation to its tool)

classes/sitemap_filter.go

@@ -51,19 +51,60 @@ func (f SitemapFilter) Decide(ctx context.Context, batch []contract.Candidate) (
 	if err != nil {
 		return nil, err
 	}
+	var pageIDs []string
+	for _, c := range batch {
+		if c.TypeKey == PageTypeKey {
+			pageIDs = append(pageIDs, c.RecordID)
+		}
+	}
+	kinds, err := pageKinds(b.db, pageIDs)
+	if err != nil {
+		return nil, err
+	}
 	for i, c := range batch {
 		d, err := b.decide(ctx, c)
 		if err != nil {
 			return nil, err
 		}
+		if c.TypeKey == PageTypeKey && !d.Exclude {
+			d.Group = PageGroup(kinds[c.RecordID])
+		}
 		out[i] = d
 	}
 	return out, nil
 }
 
-// Groups lists the file groups the decisions name.
-func (f SitemapFilter) Groups(context.Context) ([]contract.Group, error) {
-	return nil, nil
+// Groups lists the file groups the decisions name: the registry's page
+// kinds (pages, offers, services, landing-pages), titled in every locale
+// of the site with the kind's name (P33-18).
+func (f SitemapFilter) Groups(ctx context.Context) ([]contract.Group, error) {
+	var svc *Service
+	if f.Service != nil {
+		svc = f.Service()
+	}
+	if svc == nil {
+		return nil, nil
+	}
+	db, err := svc.DB(ctx)
+	if err != nil {
+		return nil, err
+	}
+	locales := svc.Locales(ctx, db)
+	tr := svc.translator()
+	out := make([]contract.Group, 0, len(models.PageKinds))
+	for _, kind := range models.PageKinds {
+		titles := map[string]string{}
+		key := PageKindLabels[kind]
+		for _, locale := range locales {
+			if tr == nil {
+				titles[locale] = key
+				continue
+			}
+			titles[locale] = tr.GetIn(locale, key, nil)
+		}
+		out = append(out, contract.Group{Key: PageGroup(kind), Titles: titles})
+	}
+	return out, nil
 }
 
 // newFilterBatch reads the settings and the redirects once for a batch.