refactor(PostPage): 将动画类从PostCard移到外部div

将动画相关的class和style属性从PostCard组件移动到包裹它的div元素，以提高组件结构的清晰度和可维护性

src/components/PostPage.astro

@@ -12,6 +12,7 @@ const interval = 50;
 <div class="transition flex flex-col rounded-[var(--radius-large)] bg-transparent gap-4 mb-4">
 
     {page.data.map((entry: CollectionEntry<"posts">) => (
+        <div class="onload-animation" style={`animation-delay: calc(var(--content-delay) + ${delay++ * interval}ms);`}>
             <PostCard
                     entry={entry}
                     title={entry.data.title}
@@ -21,8 +22,7 @@ const interval = 50;
                     image={entry.data.image}
                     description={entry.data.description}
                     draft={entry.data.draft}
-                class:list="onload-animation"
-                style={`animation-delay: calc(var(--content-delay) + ${delay++ * interval}ms);`}
             ></PostCard>
+        </div>
     ))}
 </div>