feat: pagination forms and suffixes in resolve and site

- Pagination tab: query or path form, per-locale segment, title and
  description suffixes with %page% and %pages%
- ?page=1, /<segment>/1 and the other form answer 301 to the configured
  address in one hop with normalisation and strict URLs; a page value
  that is not a number answers not_found with pagination.invalid
- page 2 and later: self canonical with the page, index,follow, the
  suffixes (%pages% left for the layer), paged hreflang alternates
- GET /site answers pagination {form, param, segments} and home_crumb

classes/site.go

@@ -15,7 +15,8 @@ import (
 // sitemap settings; Routes each content type's layered URL pattern for
 // the layer's drift check; RootFiles the file names the layer serves at
 // the site root (verification files, the IndexNow key file); LLMS whether
-// /llms.txt is served.
+// /llms.txt is served; Pagination the site's page address form and
+// HomeCrumb the home crumb (33-06, D-40, D-86).
 type SiteAnswer struct {
 	SiteURL          string          `json:"site_url"`
 	DefaultLocale    string          `json:"default_locale"`
@@ -26,6 +27,25 @@ type SiteAnswer struct {
 	Routes           []SiteRoute     `json:"routes"`
 	RootFiles        []string        `json:"root_files"`
 	LLMS             bool            `json:"llms"`
+	Pagination       SitePagination  `json:"pagination"`
+	HomeCrumb        SiteHomeCrumb   `json:"home_crumb"`
+}
+
+// SitePagination is the site answer's pagination block: the form (query
+// or path), the query parameter and the path segment per locale, so the
+// layer builds numbered links and checks drift.
+type SitePagination struct {
+	Form     string            `json:"form"`
+	Param    string            `json:"param"`
+	Segments map[string]string `json:"segments"`
+}
+
+// SiteHomeCrumb is the home crumb: its name in the default locale, the
+// home URL and the name per locale.
+type SiteHomeCrumb struct {
+	Name  string            `json:"name"`
+	URL   string            `json:"url"`
+	Names map[string]string `json:"names"`
 }
 
 // SiteLinks is the site answer's links block.
@@ -86,6 +106,13 @@ func (s *Service) Site(ctx context.Context) (SiteAnswer, error) {
 	out.Locales = s.Locales(ctx, db)
 	out.Links.NewTab = settings.LinksNewTab
 	out.LLMS = robots.LlmsEnabled
+	pages := s.PageConfigOf(ctx, db, settings)
+	out.Pagination = SitePagination{Form: pages.Form, Param: PageParam, Segments: pages.Segments}
+	out.HomeCrumb = SiteHomeCrumb{URL: out.SiteURL + "/", Names: map[string]string{}}
+	for _, locale := range out.Locales {
+		out.HomeCrumb.Names[locale] = s.HomeCrumbName(ctx, db, settings, locale)
+	}
+	out.HomeCrumb.Name = out.HomeCrumb.Names[out.DefaultLocale]
 	if reg := s.Registry(); reg != nil {
 		for _, typ := range reg.ContentTypes() {
 			if typ.Key == PageTypeKey {