feat: JSON-LD graph, breadcrumbs and hreflang in the resolve answer (tracer)

- classes/schema builds one @graph per page (WebPage, article, profile,
  service, BreadcrumbList, VideoObject, WebSite, publisher) linked by @id
- breadcrumb trail through the primary parent chain, hreflang alternates
  with x-default, html_lang and og:locale in the resolve answer
- migration 202610280004 adds the publisher, local business, home crumb
  and pagination settings columns

classes/resolver.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"unicode/utf8"
 
+	"git.golem15.com/golem15/sm-seo-plugin/classes/schema"
 	"git.golem15.com/golem15/sm-seo-plugin/models"
 	"git.golem15.com/golem15/summercms/modules/cabana"
 	"git.golem15.com/golem15/summercms/modules/pact"
@@ -64,8 +65,16 @@ type Result struct {
 	SEO      *SEO   `json:"seo"`
 	// Outbound is how the layer renders links to other sites (P33-16),
 	// present on ok answers.
-	Outbound *Outbound         `json:"outbound,omitempty"`
-	Sources  map[string]string `json:"-"`
+	Outbound *Outbound `json:"outbound,omitempty"`
+	// HTMLLang is the page's <html lang> (P33-21); Alternates its hreflang
+	// list, the page itself and x-default included (D-55 to D-57); JSONLD
+	// its one @graph (D-43); Breadcrumbs its trail, the same items as the
+	// BreadcrumbList node (D-86). All are set on ok answers only.
+	HTMLLang    string            `json:"html_lang,omitempty"`
+	Alternates  []Alternate       `json:"alternates,omitempty"`
+	JSONLD      map[string]any    `json:"jsonld,omitempty"`
+	Breadcrumbs []schema.Crumb    `json:"breadcrumbs,omitempty"`
+	Sources     map[string]string `json:"-"`
 	// TypeKey and RecordID name the record behind the URL, "" when none.
 	TypeKey  string `json:"-"`
 	RecordID string `json:"-"`
@@ -118,6 +127,10 @@ type OpenGraph struct {
 	Description string `json:"description"`
 	Image       string `json:"image"`
 	URL         string `json:"url"`
+	// Locale is og:locale (pl_PL) and LocaleAlternates the og:locale of the
+	// record's other translated locales (D-55), set on ok answers.
+	Locale           string   `json:"locale"`
+	LocaleAlternates []string `json:"locale_alternates"`
 }
 
 // TwitterTag holds the twitter: values.
@@ -679,6 +692,16 @@ func (r *Resolver) resolveAt(ctx context.Context, db *gorm.DB, settings models.S
 
 	res.Action, res.Status, res.Locale, res.SEO = ActionOK, 200, locale, seo
 	res.Outbound = OutboundOf(settings)
+	// The sitemap filter (production) decides on robots and canonical
+	// only; it skips the structured data.
+	if !r.production {
+		if err := svc.structuredData(ctx, db, settings, &res, structuredIn{
+			key: key, id: res.RecordID, rec: rec, entry: entry, content: content,
+			locale: locale, path: path, url: self, home: home, siteName: svc.SiteName(ctx, settings, locale), seo: seo,
+		}); err != nil {
+			return Result{}, err
+		}
+	}
 	return res, nil
 }