feat: expose user activity timestamps in admin list

frontend/src/i18n/locales/en.ts

@@ -1391,6 +1391,8 @@ export default {
         usage: 'Usage',
         concurrency: 'Concurrency',
         status: 'Status',
+        lastLogin: 'Last Login',
+        lastActive: 'Last Active',
         created: 'Created',
         actions: 'Actions'
       },

frontend/src/i18n/locales/zh.ts

@@ -1417,6 +1417,8 @@ export default {
         usage: '用量',
         concurrency: '并发数',
         status: '状态',
+        lastLogin: '最后登录',
+        lastActive: '最后使用',
         created: '创建时间',
         actions: '操作'
       },