Add 'recent_items' translation for multiple languages and update AiAssistant header

apps/app/public/static/locales/en_US/translation.json

@@ -606,6 +606,7 @@
     "my_assistants": "My Assistants",
     "team_assistants": "Team Assistants",
     "thread_does_not_exist": "No threads exist",
+    "recent_items": "Recent Items",
     "toaster": {
       "ai_assistant_deleted_success": "Assistant deleted",
       "ai_assistant_deleted_failed": "Failed to delete assistant",

apps/app/public/static/locales/fr_FR/translation.json

@@ -600,6 +600,7 @@
     "my_assistants": "Mes assistants",
     "team_assistants": "Assistants d'équipe",
     "thread_does_not_exist": "Aucune discussion",
+    "recent_items": "Éléments récents",
     "toaster": {
       "ai_assistant_deleted_success": "Assistant supprimé",
       "ai_assistant_deleted_failed": "Échec de la suppression de l'assistant",

apps/app/public/static/locales/ja_JP/translation.json

@@ -638,6 +638,7 @@
     "my_assistants": "マイアシスタント",
     "team_assistants": "チームアシスタント",
     "thread_does_not_exist": "スレッドが存在しません",
+    "recent_items": "最近の項目",
     "toaster": {
       "ai_assistant_deleted_success": "アシスタントを削除しました",
       "ai_assistant_deleted_failed": "アシスタントの削除に失敗しました",

apps/app/public/static/locales/zh_CN/translation.json

@@ -595,6 +595,7 @@
     "my_assistants": "我的助手",
     "team_assistants": "团队助手",
     "thread_does_not_exist": "暂无会话",
+    "recent_items": "最近的项目",
     "toaster": {
       "ai_assistant_deleted_success": "已删除助手",
       "ai_assistant_deleted_failed": "删除助手失败",

apps/app/src/features/openai/client/components/AiAssistant/Sidebar/AiAssistantSubstance.tsx

@@ -48,7 +48,7 @@ export const AiAssistantContent = (): JSX.Element => {
 
         <div>
           <h3 className="fw-bold grw-ai-assistant-substance-header">
-            最近の項目
+            {t('ai_assistant_list.recent_items')}
           </h3>
           <ThreadList />
         </div>