fix: 隐藏侧边栏菜单滚动条

- tailwind.config 添加 scrollbar-hide 工具类插件
- SidebarNav nav 元素添加 scrollbar-hide class

frontend/src/components/layout/SidebarNav.tsx

@@ -160,7 +160,7 @@ export default function SidebarNav({ mobileOpen, onClose }: { mobileOpen: boolea
         </div>
 
         {/* 导航菜单 */}
-        <nav className="flex-1 overflow-y-auto py-3 px-2 space-y-3">
+        <nav className="flex-1 overflow-y-auto py-3 px-2 space-y-3 scrollbar-hide">
           {navGroups.map((group, idx) => {
             const isExpanded = expandedGroups.has(group.title)
             const hasActiveItem = group.items.some(item => isActive(item.path))

frontend/tailwind.config.ts

@@ -1,4 +1,5 @@
 import typography from '@tailwindcss/typography'
+import plugin from 'tailwindcss/plugin'
 
 /** @type {import('tailwindcss').Config} */
 export default {
@@ -85,5 +86,16 @@ export default {
       },
     },
   },
-  plugins: [typography],
+  plugins: [
+    typography,
+    plugin(({ addUtilities }) => {
+      addUtilities({
+        '.scrollbar-hide': {
+          'scrollbar-width': 'none',
+          '-ms-overflow-style': 'none',
+          '&::-webkit-scrollbar': { display: 'none' },
+        },
+      })
+    }),
+  ],
 }