post_tags の論理削除と履歴管理を廃止 (#411) (#417)

Reviewed-on: #417
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/spec/services/youtube/sync_spec.rb

@@ -268,6 +268,10 @@ RSpec.describe Youtube::Sync do
       expect(tag_ids).to include(deerjikist_tag.id)
       expect(tag_ids).not_to include(Tag.no_deerjikist.id)
 
+      expect(PostTag.exists?(post:, tag: Tag.no_deerjikist)).to be(false)
+      expect(Tag.no_deerjikist.reload.post_count).to eq(0)
+      expect(deerjikist_tag.reload.post_count).to eq(1)
+
       expect(PostVersionRecorder).to have_received(:ensure_snapshot!).with(
         post,
         created_by_user: nil