外部タグの履歴管理方式を変更 (#445) (#480)

Co-authored-by: Codex Night Worker <codex-night@localhost>
Reviewed-on: #480
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/app/controllers/post_versions_controller.rb

@@ -100,18 +100,9 @@ class PostVersionsController < ApplicationController
 
   def external_tag_names_for snapshots
     ids = snapshots.flatten.filter_map { _1['external_tag_id'] }.uniq
-    names = ExternalTag.where(id: ids).pluck(:id, :platform, :name).to_h { |id, platform, name|
+    ExternalTag.where(id: ids).pluck(:id, :platform, :name).to_h { |id, platform, name|
       [id, "#{ platform }:#{ name }"]
     }
-    missing_ids = ids - names.keys
-
-    HistoryAccess.visible(NicoTagVersion.all)
-        .where(tag_id: missing_ids)
-        .order(:tag_id, version_no: :desc)
-        .pluck(:tag_id, :name)
-        .each { |id, name| names[id] ||= name }
-
-    names
   end
 
   def snapshot_tag_literals snapshots, tag_names, external_tag_names