feat: 添加预览效果页面并优化交互效果

refactor: 优化代码健壮性和类型安全

style: 更新字体样式和全局CSS

fix: 修复IntersectionObserver潜在空引用问题

chore: 更新依赖和ESLint配置

build: 更新构建ID和路由配置

src/app/(marketing)/about/page.tsx

@@ -134,7 +134,7 @@ export default function AboutPage() {
                     <div className="font-semibold text-black text-sm md:text-base">{milestone.date}</div>
                   </div>
                   <div className="flex-1 pb-6 border-l-2 border-gray-200 pl-6 relative">
-                    <div className="absolute -left-[9px] top-1 w-4 h-4 bg-black rounded-full"></div>
+                    <div className="absolute -left-[9px] top-1 w-4 h-4 bg-black rounded-full" />
                     <h3 className="font-semibold text-black mb-1">{milestone.title}</h3>
                     <p className="text-gray-600 text-sm leading-relaxed">{milestone.description}</p>
                   </div>