feat: 优化展会演示前端界面和功能

主要更新:
- 重新设计首页UI，采用现代黑色科技风格
- 修复结果弹窗按钮显示问题，固定在底部
- 添加Duoduo Agent Logo和三击调试功能
- 添加右下角浮动查看结果按钮
- 优化功能卡片布局和对齐
- 简化按钮文字为'开始'
- 移除首页演示案例内容
- 创建Windows启动脚本start_cn.bat

技术改进:
- 使用深色主题配色方案
- 添加网格背景和动态光效
- 优化组件动画效果
- 改进响应式布局

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

web_frontend/exhibition-demo/src/components/ResultModal.tsx

@@ -47,9 +47,9 @@ const ResultModal: React.FC<ResultModalProps> = ({ isOpen, onClose, onViewDetail
             className="fixed inset-0 flex items-center justify-center z-50 p-4"
             onClick={(e) => e.stopPropagation()}
           >
-            <div className="bg-white rounded-2xl shadow-2xl max-w-2xl w-full max-h-[90vh] overflow-hidden">
+            <div className="bg-white rounded-2xl shadow-2xl max-w-2xl w-full max-h-[90vh] overflow-hidden flex flex-col">
               {/* 头部 */}
-              <div className="relative bg-gradient-to-br from-green-500 to-emerald-600 p-8 text-white">
+              <div className="relative bg-gradient-to-br from-green-500 to-emerald-600 p-8 text-white flex-shrink-0">
                 <button
                   onClick={onClose}
                   className="absolute top-4 right-4 p-2 hover:bg-white/20 rounded-lg transition-colors"
@@ -74,7 +74,7 @@ const ResultModal: React.FC<ResultModalProps> = ({ isOpen, onClose, onViewDetail
                 </p>
               </div>
 
-              <div className="p-6">
+              <div className="p-6 overflow-y-auto flex-1">
                 {/* 统计信息 */}
                 <div className="grid grid-cols-3 gap-4 mb-6">
                   {stats.map((stat, index) => (
@@ -138,11 +138,13 @@ const ResultModal: React.FC<ResultModalProps> = ({ isOpen, onClose, onViewDetail
                     </div>
                   </div>
                 </div>
+              </div>
 
-                {/* 操作按钮 */}
+              {/* 操作按钮 - 固定在底部 */}
+              <div className="p-6 bg-gray-50 border-t border-gray-200 flex-shrink-0">
                 <div className="flex justify-center">
                   <button
-                    onClick={() => window.open('http://localhost:4155', '_blank')}
+                    onClick={() => window.open('http://localhost:4155/index.html', '_blank')}
                     className="px-8 py-3 bg-gradient-to-r from-blue-600 to-purple-600 text-white rounded-xl font-medium hover:shadow-lg transform hover:scale-105 transition-all flex items-center justify-center gap-2"
                   >
                     <Eye className="w-5 h-5" />