feat(gateway): 创建/编辑网关后立即异步探活健康状态

- POST/PUT /api/gateways 成功后后台立即探活一次 /healthz 并覆盖落库，不阻塞请求
- probeAndRecordGateway 抽出单网关探活+落库复用；探活超时改为 var 供测试注入
- 网关页保存成功后延迟 2.5s 刷新一次，尽快展示最新健康状态
- 测试：立即探活、慢网关不阻塞、不可达落 unhealthy

web/src/pages/gateways/index.tsx

@@ -1,5 +1,5 @@
 // 网关管理：语义对齐 web.archived GatewaysPage.jsx（注册/编辑 Modal、令牌显隐复制、删除）。
-import { useCallback, useEffect, useState } from 'react';
+import { useCallback, useEffect, useRef, useState } from 'react';
 import { Alert, App, Button, Card, Flex, Form, Input, Modal, Popconfirm, Space, Table, Tag, Tooltip, Typography } from 'antd';
 import { CopyOutlined, EyeInvisibleOutlined, EyeOutlined, PlusOutlined } from '@ant-design/icons';
 import type { ColumnsType } from 'antd/es/table';
@@ -96,6 +96,7 @@ export default function Page() {
   const [created, setCreated] = useState<any>(null);
   const { message: messageApi } = App.useApp();
   const { vertical, horizontal } = useOverflowGrid(gateways.length);
+  const healthReloadTimer = useRef<ReturnType<typeof setTimeout>>(undefined);
 
   const load = useCallback(async () => {
     setPending(true);
@@ -110,6 +111,13 @@ export default function Page() {
     }
   }, []);
 
+  // 创建/编辑后的立即探活在后台异步进行：延迟刷新一次让健康状态列尽快显示最新结果。
+  const scheduleHealthReload = useCallback(() => {
+    clearTimeout(healthReloadTimer.current);
+    healthReloadTimer.current = setTimeout(load, 2500);
+  }, [load]);
+  useEffect(() => () => clearTimeout(healthReloadTimer.current), []);
+
   useEffect(() => {
     load();
   }, [load]);
@@ -120,6 +128,7 @@ export default function Page() {
       const record = await create('gateways', values);
       setCreated(record?.data ?? record);
       await load();
+      scheduleHealthReload();
       setCreateOpen(false);
       return true;
     } catch (reason) {
@@ -136,6 +145,7 @@ export default function Page() {
     try {
       await update('gateways', editing.name, values);
       await load();
+      scheduleHealthReload();
       setEditing(null);
       return true;
     } catch (reason) {