feat: 添加功能和修复问题

- 添加全局 API Token 认证支持 (环境变量 API_TOKEN)
- Team 页面添加直接邀请按钮
- Team 页面添加随机邀请按钮
- 修复已邀请用户列表字段名不匹配问题
- 修复数据库为空时错误显示 toast 的问题

frontend/src/views/admin/CardKeysPage.vue

@@ -116,8 +116,8 @@ async function loadCardKeys() {
   loading.value = true
   try {
     const response = await getCardKeys({ page: currentPage.value, page_size: pageSize.value })
-    if (response.data.success && response.data.keys) {
-      cardKeys.value = response.data.keys
+    if (response.data.success) {
+      cardKeys.value = response.data.keys || []
       total.value = response.data.total || 0
     } else {
       toast.error(response.data.message || '获取卡密列表失败')