feat: 抽取 plan-card 为独立组件并优化样式

主要改动：
1. 创建独立的 planCard.ts 组件
   - 导出 getPlanCardStyles() 和 getPlanCardScript()
   - 包含 renderPlanCardInSegment 和 renderPlanCardStatic 两个渲染函数

2. 优化 messageArea.ts
   - 移除原有的 plan-card 内联样式和脚本（约 80 行）
   - 引入 planCard 组件并调用其函数
   - 添加 addRule 和 updateNode 工具映射

3. 优化计划卡片样式
   - 调整外边距：segment-plan 从 8px 增加到 12px
   - 优化内边距：header 12px 16px，body 16px，actions 14px 16px
   - 改进按钮布局：使用垂直布局，按钮和输入框分行显示
   - 增加元素间距：步骤间距 6px，按钮间距 10px
   - 添加行高 1.5 提升可读性

4. 添加 plannerIconSvg 图标

src/constants/toolIcons.ts

@@ -76,3 +76,8 @@ export const stopIconSvg = `
  */
 export const agentIconSvg = `
 <svg t="1767101071638" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="7779" width="16" height="16" style="display: inline-block; vertical-align: middle;"><path d="M173.474909 410.414545c-20.293818 0-33.838545-13.498182-33.838545-33.792v-135.377454C139.636364 187.066182 187.019636 139.636364 241.198545 139.636364h135.447273c20.270545 0 33.815273 13.591273 33.815273 33.885091s-13.591273 33.838545-33.885091 33.838545h-135.447273c-20.317091 0-33.815273 13.591273-33.815272 33.885091v135.377454c0.046545 20.293818-13.498182 33.792-33.838546 33.792z m203.101091 473.902546h-135.447273C187.042909 884.317091 139.636364 836.933818 139.636364 782.754909V647.447273c0-20.386909 13.544727-33.838545 33.838545-33.838546s33.885091 13.451636 33.885091 33.838546v135.330909c0 20.293818 13.544727 33.931636 33.838545 33.931636h135.447273c20.270545 0 33.815273 13.451636 33.815273 33.745455-0.046545 20.340364-13.591273 33.885091-33.885091 33.885091z m406.178909 0H647.447273c-20.386909 0-33.931636-13.544727-33.931637-33.931636 0-20.293818 13.544727-33.745455 33.931637-33.745455h135.330909c20.386909 0 33.838545-13.637818 33.838545-33.931636V647.447273c0-20.386909 13.544727-33.838545 33.931637-33.838546 20.293818 0 33.838545 13.451636 33.838545 33.838546v135.330909c-0.046545 54.178909-47.522909 101.562182-101.608727 101.562182z m67.723636-473.902546c-20.386909 0-33.931636-13.498182-33.931636-33.792v-135.377454c0-20.340364-13.451636-33.885091-33.838545-33.885091H647.447273c-20.386909 0-33.931636-13.498182-33.931637-33.838545S627.083636 139.636364 647.424 139.636364h135.330909c54.085818 0 101.562182 47.429818 101.562182 101.608727v135.377454c0 20.293818-13.544727 33.792-33.838546 33.792z m0 135.493819H173.474909c-20.293818 0-33.838545-13.591273-33.838545-33.931637s13.544727-33.885091 33.838545-33.885091h677.003636c20.293818 0 33.838545 13.591273 33.838546 33.885091s-13.544727 33.931636-33.838546 33.931637z" fill="#8a8a8a" p-id="7780"></path></svg>`;
+
+/**
+ * planner 图标 SVG
+ */
+export const plannerIconSvg = `<svg t="1767143425474" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="10954" width="16" height="16"><path d="M860.544 633.856c-82.368 0-152.128 69.632-158.464 152h-354.88c-31.616 0-63.296-31.68-63.296-63.296V437.376c12.608 0 25.344 6.4 44.288 6.4h380.16c12.672 69.696 76.032 126.656 152.128 126.656 88.704 0 158.336-69.696 158.336-158.4s-69.632-158.4-158.336-158.4c-76.096 0-139.456 57.024-152.128 126.656h-361.216c-31.616 0-63.296-31.68-63.296-63.296v-133.12h164.736c31.68 0 63.296-22.848 63.296-54.528a55.04 55.04 0 0 0-56-56h-380.16c-31.68 0-70.72 17.984-70.72 56s31.68 54.528 63.36 54.528h133.056v538.624c0 69.696 57.088 126.656 126.72 126.656h386.56c25.344 57.088 82.368 101.376 145.728 101.376a156.8 156.8 0 0 0 158.336-158.4 156.608 156.608 0 0 0-158.208-158.272z m0-316.8c50.624 0 94.912 44.288 94.912 94.976s-44.288 94.976-94.912 94.976c-50.752 0-95.104-44.288-95.104-94.976s44.352-94.976 95.104-94.976z m0 570.24c-50.752 0-95.104-44.352-95.104-95.04s44.352-95.04 95.104-95.04c50.624 0 94.912 44.352 94.912 95.04s-44.288 95.04-94.912 95.04z" p-id="10955" fill="#8a8a8a"></path></svg>`;