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

@@ -12,17 +12,17 @@ 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">) => (
-        <PostCard
-                entry={entry}
-                title={entry.data.title}
-                published={entry.data.published}
-                updated={entry.data.updated}
-                url={getPostUrlBySlug(entry.slug)}
-                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 class="onload-animation" style={`animation-delay: calc(var(--content-delay) + ${delay++ * interval}ms);`}>
+            <PostCard
+                    entry={entry}
+                    title={entry.data.title}
+                    published={entry.data.published}
+                    updated={entry.data.updated}
+                    url={getPostUrlBySlug(entry.slug)}
+                    image={entry.data.image}
+                    description={entry.data.description}
+                    draft={entry.data.draft}
+            ></PostCard>
+        </div>
     ))}
 </div>