feat: graph validation and custom JSON-LD

- seo_schema (seoschema, E8) with the C17 server rules: invalid JSON with
  line and column, non-objects, 16 KB, depth 8, a literal <script and a
  type outside the kind's list refused; the value re-serialised
- a custom node with a generated @id merges into it (schema.merged save
  notice), other nodes are appended to the graph
- seo_primary_parent (seoparent) for article types; both values stored
  in the entry data on every locale row
- the seo_graph widget action (E9 data), P1 primary_gone and the P2
  schema type and breadcrumb trail rows
- GET /_seo/api/v1/graph and MCP seo_get_graph; seo_set_url_seo and
  apply_batch accept primary_parent and schema

The graph tool lands with the validation: the operations parity test
binds the seo_graph widget action to its tool.

classes/partials.go

@@ -7,6 +7,7 @@ import (
 	"reflect"
 	"strings"
 
+	"git.golem15.com/golem15/sm-seo-plugin/classes/schema"
 	"git.golem15.com/golem15/sm-seo-plugin/models"
 	"git.golem15.com/golem15/sm-sitemap-plugin/contract"
 	"gorm.io/gorm"
@@ -104,7 +105,7 @@ func (s *Service) EffectiveRows(ctx context.Context, res Result) []EffectiveRow
 		"title": res.SEO.Title, "description": res.SEO.Description, "canonical": res.SEO.Canonical,
 		"robots": res.SEO.Robots, "og_title": res.SEO.OG.Title, "og_description": res.SEO.OG.Description, "og_image": res.SEO.OG.Image,
 	}
-	out := make([]EffectiveRow, 0, len(effectiveProperties))
+	out := make([]EffectiveRow, 0, len(effectiveProperties)+2)
 	for _, p := range effectiveProperties {
 		out = append(out, EffectiveRow{
 			Property: s.PhraseCtx(ctx, p.label, nil),
@@ -113,9 +114,47 @@ func (s *Service) EffectiveRows(ctx context.Context, res Result) []EffectiveRow
 			Mono:     p.mono,
 		})
 	}
+	// Structured data (UI-SPEC C16): the page's schema type and its
+	// breadcrumb trail.
+	if res.JSONLD != nil {
+		typ, source := effectiveSchemaType(res), SourceDefault
+		if res.Sources["schema"] != "" {
+			source = res.Sources["schema"]
+		}
+		out = append(out, EffectiveRow{
+			Property: s.PhraseCtx(ctx, "golem15.seo::lang.effective.schema", nil),
+			Value:    typ,
+			Source:   s.PhraseCtx(ctx, "golem15.seo::lang.effective.source_"+source, nil),
+		})
+		names := make([]string, 0, len(res.Breadcrumbs))
+		for _, c := range res.Breadcrumbs {
+			names = append(names, c.Name)
+		}
+		out = append(out, EffectiveRow{
+			Property: s.PhraseCtx(ctx, "golem15.seo::lang.effective.trail", nil),
+			Value:    strings.Join(names, " › "),
+			Source:   s.PhraseCtx(ctx, "golem15.seo::lang.effective.source_"+SourceContent, nil),
+		})
+	}
 	return out
 }
 
+// effectiveSchemaType is the page's main schema type: its article or
+// service node, else its page node.
+func effectiveSchemaType(res Result) string {
+	page := ""
+	for _, n := range schema.Nodes(res.JSONLD) {
+		id, _ := n["@id"].(string)
+		switch id {
+		case res.URL + "#article", res.URL + "#service":
+			return schema.NodeType(n)
+		case res.URL + "#webpage":
+			page = schema.NodeType(n)
+		}
+	}
+	return page
+}
+
 // newEffectiveView starts a P2 view with its labels and the staging note.
 func (s *Service) newEffectiveView(ctx context.Context) EffectiveView {
 	return EffectiveView{
@@ -205,6 +244,9 @@ func (s *Service) RecordStatus(ctx context.Context, key, id string) (StatusView,
 			}
 		}
 	}
+	if c, ok := s.primaryGoneCallout(ctx, db, key, id); ok {
+		view.Callouts = append(view.Callouts, c)
+	}
 	exclusions, err := s.RecordSitemapExclusions(ctx, key, id)
 	if err != nil {
 		return view, err
@@ -346,3 +388,42 @@ func RecordKey(db *gorm.DB, record any) (string, error) {
 func reflectValue(record any) reflect.Value {
 	return reflect.Indirect(reflect.ValueOf(record))
 }
+
+// primaryGoneCallout warns that a record's stored primary category is no
+// longer one of its parents, so the first one is used (UI-SPEC C16).
+func (s *Service) primaryGoneCallout(ctx context.Context, db *gorm.DB, key, id string) (Callout, bool) {
+	reg := s.Registry()
+	if reg == nil {
+		return Callout{}, false
+	}
+	typ, ok := reg.ContentType(key)
+	if !ok || typ.Content == nil {
+		return Callout{}, false
+	}
+	entries, err := LoadEntries(db, typ.Content.Model, id)
+	if err != nil {
+		return Callout{}, false
+	}
+	stored := SharedData(entries, DataPrimaryParent)
+	if stored == "" {
+		return Callout{}, false
+	}
+	rec, err := reg.Describe(ctx, key, id, s.UnprefixedLocale())
+	if err != nil || rec == nil {
+		return Callout{}, false
+	}
+	if _, _, gone := PrimaryParent(rec, stored); !gone {
+		return Callout{}, false
+	}
+	name := stored
+	if pt, pid, ok := strings.Cut(stored, ":"); ok {
+		if parent, err := reg.Describe(ctx, pt, pid, s.UnprefixedLocale()); err == nil && parent != nil {
+			if l := contentLocale(parent, s.DefaultLocale(ctx, db)); strings.TrimSpace(l.Title) != "" {
+				name = l.Title
+			}
+		}
+	}
+	return Callout{
+		Title: s.PhraseCtx(ctx, "golem15.seo::lang.status.primary_gone", map[string]string{"name": name}),
+	}, true
+}