fix(frontend): 修复DataTable无限循环和i18n邮箱解析错误

- 修复DataTable组件watch监听actionsExpanded导致的无限循环卡死问题
- 为AccountsView和UsersView添加actionsCount属性启用操作列展开功能
- 修复i18n翻译中邮箱地址的@符号未转义导致的编译错误

frontend/src/components/common/DataTable.vue

@@ -257,9 +257,10 @@ const sortKey = ref<string>('')
 const sortOrder = ref<'asc' | 'desc'>('asc')
 const actionsExpanded = ref(false)
 
-// 数据/列/展开状态变化时重新检查滚动状态
+// 数据/列变化时重新检查滚动状态
+// 注意：不能监听 actionsExpanded，因为 checkActionsColumnWidth 会临时修改它，会导致无限循环
 watch(
-  [() => props.data.length, () => props.columns, actionsExpanded],
+  [() => props.data.length, () => props.columns],
   async () => {
     await nextTick()
     checkScrollable()
@@ -268,6 +269,12 @@ watch(
   { flush: 'post' }
 )
 
+// 单独监听展开状态变化，只更新滚动状态
+watch(actionsExpanded, async () => {
+  await nextTick()
+  checkScrollable()
+})
+
 const handleSort = (key: string) => {
   if (sortKey.value === key) {
     sortOrder.value = sortOrder.value === 'asc' ? 'desc' : 'asc'