re-add mistakenly removed code

shared/models.py

@@ -495,6 +495,7 @@ class ArticlesMixin:
 
         key_fields_default_values = {
             "union_thumb_image_id": F("search_image_id"),
+            "union_article_type": Value(2, models.PositiveSmallIntegerField()),
         }
 
         create_complementary_field = lambda key: (