feat: add BigScreen 2D/3D links to sidebar navigation

Added "可视化大屏" submenu with "2D 能源大屏" and "3D 园区大屏" entries.
BigScreen pages open in new browser tabs since they are full-screen views.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/layouts/MainLayout.tsx

@@ -5,7 +5,7 @@ import {
   FileTextOutlined, CloudOutlined, SettingOutlined, UserOutlined,
   MenuFoldOutlined, MenuUnfoldOutlined, LogoutOutlined, BellOutlined,
   ThunderboltOutlined, AppstoreOutlined, WarningOutlined, CloseCircleOutlined,
-  InfoCircleOutlined,
+  InfoCircleOutlined, FundProjectionScreenOutlined, GlobalOutlined,
 } from '@ant-design/icons';
 import { Outlet, useNavigate, useLocation } from 'react-router-dom';
 import { getUser, removeToken } from '../utils/auth';
@@ -22,6 +22,12 @@ const menuItems = [
   { key: '/alarms', icon: <AlertOutlined />, label: '告警管理' },
   { key: '/carbon', icon: <CloudOutlined />, label: '碳排放管理' },
   { key: '/reports', icon: <FileTextOutlined />, label: '报表管理' },
+  { key: 'bigscreen-group', icon: <FundProjectionScreenOutlined />, label: '可视化大屏',
+    children: [
+      { key: '/bigscreen', icon: <FundProjectionScreenOutlined />, label: '2D 能源大屏' },
+      { key: '/bigscreen-3d', icon: <GlobalOutlined />, label: '3D 园区大屏' },
+    ],
+  },
   { key: '/system', icon: <SettingOutlined />, label: '系统管理',
     children: [
       { key: '/system/users', label: '用户管理' },
@@ -103,7 +109,13 @@ export default function MainLayout() {
           selectedKeys={[location.pathname]}
           defaultOpenKeys={['/system']}
           items={menuItems}
-          onClick={({ key }) => navigate(key)}
+          onClick={({ key }) => {
+            if (key === '/bigscreen' || key === '/bigscreen-3d') {
+              window.open(key, '_blank');
+            } else {
+              navigate(key);
+            }
+          }}
         />
       </Sider>
       <Layout>