refactor(ui): clean up unused imports and variables in UI components

src/pages/Roles.tsx

@@ -12,7 +12,7 @@ import {
   TableHeader,
   TableRow,
 } from '@/components/ui/table'
-import { RefreshCw, Loader2, Users, Shield, Check } from 'lucide-react'
+import { RefreshCw, Loader2, Users, Check } from 'lucide-react'
 
 // 角色颜色映射
 const roleColors: Record<string, { bg: string; text: string; border: string }> = {