feat(admin): Admin V2 — Ant Design Pro 纯 SPA 重写

Next.js SSR/hydration 与 SWR fetch-on-mount 存在根本冲突：
hydration 卸载组件时 abort 的请求仍占用后端 DB 连接，
retry 循环耗尽 PostgreSQL 连接池导致后端完全卡死。

admin-v2 使用 Vite + React + antd 纯 SPA 彻底消除此问题：
- 12 页面全部完成（Login, Dashboard, Accounts, Providers, Models,
  API Keys, Usage, Relay, Config, Prompts, Logs, Agent Templates）
- ProTable + ProForm + ProLayout 统一 UI 模式
- TanStack Query + Axios + Zustand 数据层
- JWT 自动刷新 + 401 重试机制
- 全部 18 网络请求 200 OK，零 ERR_ABORTED

同时更新 troubleshooting 第 13 节和 SaaS 平台文档。

admin-v2/src/layouts/AdminLayout.tsx

@@ -0,0 +1,103 @@
+// ============================================================
+// AdminLayout — ProLayout 管理后台布局
+// ============================================================
+
+import { Outlet, useNavigate, useLocation } from 'react-router-dom'
+import ProLayout from '@ant-design/pro-layout'
+import {
+  DashboardOutlined,
+  TeamOutlined,
+  CloudServerOutlined,
+  ApiOutlined,
+  KeyOutlined,
+  BarChartOutlined,
+  SwapOutlined,
+  SettingOutlined,
+  FileTextOutlined,
+  MessageOutlined,
+  RobotOutlined,
+  LogoutOutlined,
+} from '@ant-design/icons'
+import { useAuthStore } from '@/stores/authStore'
+import { Avatar, Dropdown, message } from 'antd'
+import type { MenuDataItem } from '@ant-design/pro-layout'
+
+const menuConfig: MenuDataItem[] = [
+  { path: '/', name: '仪表盘', icon: <DashboardOutlined /> },
+  { path: '/accounts', name: '账号管理', icon: <TeamOutlined />, permission: 'account:admin' },
+  { path: '/providers', name: '服务商', icon: <CloudServerOutlined />, permission: 'provider:manage' },
+  { path: '/models', name: '模型管理', icon: <ApiOutlined />, permission: 'model:read' },
+  { path: '/agent-templates', name: 'Agent 模板', icon: <RobotOutlined />, permission: 'model:read' },
+  { path: '/api-keys', name: 'API 密钥', icon: <KeyOutlined />, permission: 'admin:full' },
+  { path: '/usage', name: '用量统计', icon: <BarChartOutlined />, permission: 'admin:full' },
+  { path: '/relay', name: '中转任务', icon: <SwapOutlined />, permission: 'relay:use' },
+  { path: '/config', name: '系统配置', icon: <SettingOutlined />, permission: 'config:read' },
+  { path: '/prompts', name: '提示词管理', icon: <MessageOutlined />, permission: 'prompt:read' },
+  { path: '/logs', name: '操作日志', icon: <FileTextOutlined />, permission: 'admin:full' },
+]
+
+function filterMenuByPermission(
+  items: MenuDataItem[],
+  hasPermission: (p: string) => boolean,
+): MenuDataItem[] {
+  return items
+    .filter((item) => !item.permission || hasPermission(item.permission as string))
+    .map(({ permission, ...rest }) => ({
+      ...rest,
+      children: rest.children ? filterMenuByPermission(rest.children, hasPermission) : undefined,
+    }))
+}
+
+export default function AdminLayout() {
+  const navigate = useNavigate()
+  const location = useLocation()
+  const { account, hasPermission, logout } = useAuthStore()
+
+  const menuData = filterMenuByPermission(menuConfig, hasPermission)
+
+  const handleLogout = () => {
+    logout()
+    message.success('已退出登录')
+    navigate('/login', { replace: true })
+  }
+
+  return (
+    <ProLayout
+      title="ZCLAW"
+      logo={<div style={{ width: 28, height: 28, background: '#1677ff', borderRadius: 6, display: 'flex', alignItems: 'center', justifyContent: 'center', color: '#fff', fontWeight: 700, fontSize: 14 }}>Z</div>}
+      layout="mix"
+      fixSiderbar
+      fixedHeader
+      location={{ pathname: location.pathname }}
+      menuDataRender={() => menuData}
+      menuItemRender={(item, dom) => (
+        <div onClick={() => item.path && navigate(item.path)}>{dom}</div>
+      )}
+      avatarProps={{
+        src: undefined,
+        title: account?.display_name || account?.username || 'Admin',
+        size: 'small',
+        render: (_, dom) => (
+          <Dropdown
+            menu={{
+              items: [
+                {
+                  key: 'logout',
+                  icon: <LogoutOutlined />,
+                  label: '退出登录',
+                  onClick: handleLogout,
+                },
+              ],
+            }}
+          >
+            {dom}
+          </Dropdown>
+        ),
+      }}
+      suppressSiderWhenMenuEmpty
+      contentStyle={{ padding: 24 }}
+    >
+      <Outlet />
+    </ProLayout>
+  )
+}