style(agent): 优化工作流页面样式

- 移除工作流卡片标题的自定义颜色样式- 优化 Markdown 渲染容器的样式，确保图片自适应- 调整历史记录项弹出框的样式，使其背景透明无圆角

src/views/agent/work-flow/index.vue

@@ -42,7 +42,7 @@
                 {{ item.title }}
               </div>
               <div class="trigger-container">
-                <a-trigger position="top" trigger="click" :auto-fit-position="false" :unmount-on-close="true ">
+                <a-trigger mouse-leave-delay="200" position="top" trigger="hover" :auto-fit-position="false" :unmount-on-close="true ">
                   <SvgIcon size="12" name="svg-more"  class="icon-more"  />
                   <template #content>
                     <div class="">

src/views/agent/work-flow/style.scss

@@ -227,7 +227,7 @@
           }
           .trigger-container {
             .icon-more {
-              display: none;
+              visibility: hidden;
               float: right;
               cursor: pointer;
             }
@@ -235,7 +235,7 @@
           &:hover {
             background: var(--BG-200, #E6E6E8);
             .trigger-container .icon-more {
-              display: block;
+              visibility: visible;
             }
           }