chore: refactoring and tests, splitting up files (#12495)

packages/app/src/i18n/ja.ts

@@ -28,8 +28,8 @@ export const dict = {
   "command.settings.open": "設定を開く",
   "command.session.previous": "前のセッション",
   "command.session.next": "次のセッション",
-  "command.session.previous.unseen": "Previous unread session",
-  "command.session.next.unseen": "Next unread session",
+  "command.session.previous.unseen": "前の未読セッション",
+  "command.session.next.unseen": "次の未読セッション",
   "command.session.archive": "セッションをアーカイブ",
 
   "command.palette": "コマンドパレット",