style(layout): 移除侧边栏标题中的图标

- 移除了侧边栏标题区域的 Sparkles 图标元素
- 保留了标题文字 "DataBuilder知识应用管理系统"
- 简化了侧边栏头部的布局结构

frontend/src/pages/Layout/Sidebar.tsx

@@ -74,9 +74,6 @@ const AsiderAndHeaderLayout = () => {
       <div className="flex items-center justify-between p-4 border-b border-gray-200">
         {sidebarOpen && (
           <NavLink to="/" className="flex items-center gap-2 cursor-pointer">
-            <div className="w-8 h-8 bg-gradient-to-br from-blue-500 to-indigo-600 rounded-lg flex items-center justify-center">
-              <Sparkles className="w-5 h-5 text-white" />
-            </div>
             <span className="text-lg font-bold text-gray-900">DataBuilder知识应用管理系统</span>
           </NavLink>
         )}