feat(14.2.1-06): persist nested ML maps on relation-child create

RelationService looks up TranslationWriter like CRUDService so CreateChild can lift locale maps before fillChild, write Polish after the child PK, and return a hydrated title map.

Co-authored-by: Cursor <cursoragent@cursor.com>

modules/cabana/http.go

@@ -656,7 +656,13 @@ func (s *service) relations() (RelationService, error) {
 	if err != nil {
 		return RelationService{}, err
 	}
-	return RelationService{DB: db, bucket: s.bucket(), tr: s.translator()}, nil
+	svc := RelationService{DB: db, bucket: s.bucket(), tr: s.translator()}
+	if s.app != nil {
+		if w, ok := s.app.Lookup[TranslationWriter](); ok {
+			svc.writer = w
+		}
+	}
+	return svc, nil
 }
 
 // relationsFor is the relation service of one request, carrying its