feat: create PostElement component for blog post display

- Added a new PostElement component to render individual blog posts with title, publication date, and reading time.
- Updated the blog index page to utilize PostElement instead of PostSummary for improved post presentation.

src/pages/blog/index.astro

@@ -1,7 +1,7 @@
 ---
 import { getCollection } from "astro:content";
 import Layout from "../../layouts/BaseLayout.astro";
-import PostSummary from "../../components/PostSummary.astro";
+import PostElement from "../../components/PostElement.astro";
 
 const posts = await getCollection("blog", ({ data }) => {
 	return data.draft !== true;
@@ -12,6 +12,8 @@ posts.sort((a, b) => b.data.pubDate.getTime() - a.data.pubDate.getTime());
 
 <Layout>
 	<section style={{ "margin-top": "3rem" }}>
-		{posts.map((post) => <PostSummary post={post} />)}
+		<ul>
+			{posts.map((post) => <PostElement post={post} />)}
+		</ul>
 	</section>
 </Layout>