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

updates/202610280004_add_golem15_seo_publisher_pagination.go

@@ -0,0 +1,65 @@
+package updates
+
+import (
+	"github.com/go-gormigrate/gormigrate/v2"
+	"gorm.io/gorm"
+)
+
+// addPublisherPagination adds the settings columns of the structured data,
+// breadcrumb and pagination plan (33-06): the home crumb name, the page
+// address form and its per-locale segment and suffixes, the publisher
+// (D-45) and its local business data (opening hours as a JSON list). The
+// translatable text columns (breadcrumb_home, page_segment, the suffixes,
+// publisher_name) hold the default locale; the others live with the
+// translation writer, as site_name does. Empty texts mean the per-locale
+// default copy.
+var addPublisherPagination = []*gormigrate.Migration{
+	{
+		ID: "202610280004_add_golem15_seo_publisher_pagination",
+		Migrate: func(tx *gorm.DB) error {
+			return tx.Exec(`ALTER TABLE golem15_seo_settings
+	ADD COLUMN breadcrumb_home TEXT NOT NULL DEFAULT '',
+	ADD COLUMN page_form TEXT NOT NULL DEFAULT 'query',
+	ADD COLUMN page_segment TEXT NOT NULL DEFAULT '',
+	ADD COLUMN page_title_suffix TEXT NOT NULL DEFAULT '',
+	ADD COLUMN page_description_suffix TEXT NOT NULL DEFAULT '',
+	ADD COLUMN publisher_type TEXT NOT NULL DEFAULT 'organization',
+	ADD COLUMN publisher_name TEXT NOT NULL DEFAULT '',
+	ADD COLUMN publisher_logo TEXT NOT NULL DEFAULT '',
+	ADD COLUMN publisher_url TEXT NOT NULL DEFAULT '',
+	ADD COLUMN publisher_email TEXT NOT NULL DEFAULT '',
+	ADD COLUMN publisher_phone TEXT NOT NULL DEFAULT '',
+	ADD COLUMN publisher_same_as TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_enabled BOOLEAN NOT NULL DEFAULT FALSE,
+	ADD COLUMN local_type TEXT NOT NULL DEFAULT 'LocalBusiness',
+	ADD COLUMN local_price_range TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_street TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_postal_code TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_city TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_region TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_country TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_latitude TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_longitude TEXT NOT NULL DEFAULT '',
+	ADD COLUMN local_hours JSONB NULL`).Error
+		},
+		Rollback: func(tx *gorm.DB) error {
+			return tx.Exec(`ALTER TABLE golem15_seo_settings
+	DROP COLUMN IF EXISTS breadcrumb_home, DROP COLUMN IF EXISTS page_form,
+	DROP COLUMN IF EXISTS page_segment, DROP COLUMN IF EXISTS page_title_suffix,
+	DROP COLUMN IF EXISTS page_description_suffix, DROP COLUMN IF EXISTS publisher_type,
+	DROP COLUMN IF EXISTS publisher_name, DROP COLUMN IF EXISTS publisher_logo,
+	DROP COLUMN IF EXISTS publisher_url, DROP COLUMN IF EXISTS publisher_email,
+	DROP COLUMN IF EXISTS publisher_phone, DROP COLUMN IF EXISTS publisher_same_as,
+	DROP COLUMN IF EXISTS local_enabled, DROP COLUMN IF EXISTS local_type,
+	DROP COLUMN IF EXISTS local_price_range, DROP COLUMN IF EXISTS local_street,
+	DROP COLUMN IF EXISTS local_postal_code, DROP COLUMN IF EXISTS local_city,
+	DROP COLUMN IF EXISTS local_region, DROP COLUMN IF EXISTS local_country,
+	DROP COLUMN IF EXISTS local_latitude, DROP COLUMN IF EXISTS local_longitude,
+	DROP COLUMN IF EXISTS local_hours`).Error
+		},
+	},
+}
+
+func init() {
+	Register(addPublisherPagination...)
+}