优化导航栏缩小按钮

frontend/src/layouts/MainLayout.tsx

@@ -13,10 +13,9 @@ import {
   AppstoreOutlined,
   DashboardOutlined,
   DownOutlined,
-  LeftOutlined,
   LogoutOutlined,
+  MenuOutlined,
   OrderedListOutlined,
-  RightOutlined,
   ShopOutlined,
   TeamOutlined,
   UserOutlined,
@@ -227,14 +226,6 @@ export default function MainLayout() {
         width={230}
         collapsedWidth={74}
       >
-        <button
-          className="app-sidebar__collapse"
-          type="button"
-          onClick={() => setCollapsed(!collapsed)}
-          aria-label={collapsed ? '展开侧边栏' : '收起侧边栏'}
-        >
-          {collapsed ? <RightOutlined /> : <LeftOutlined />}
-        </button>
         <div className="app-sidebar__brand">
           <span className="app-sidebar__brand-mark">S</span>
           {!collapsed ? <span className="app-sidebar__brand-text">Skin Hub</span> : null}
@@ -282,6 +273,15 @@ export default function MainLayout() {
         <Header
           className="app-header"
         >
+          <button
+            className="app-header__collapse"
+            type="button"
+            onClick={() => setCollapsed(!collapsed)}
+            aria-label={collapsed ? '展开侧边栏' : '收起侧边栏'}
+            title={collapsed ? '展开侧边栏' : '收起侧边栏'}
+          >
+            <MenuOutlined />
+          </button>
           <Dropdown menu={{ items: userMenu }}>
             <Space style={{ cursor: 'pointer' }}>
               <Avatar size="small" icon={<UserOutlined />} />