Optimization & UI/UX improvements for Blog Index Page

[vnphanquang]

• [ ] for blog post item, utilize @container queries, reduce font-size in horizontal layout variant, and change aspect ratio of image to be square.
• [ ] add border between columns at highlighted (recent) posts section
• [ ] reduce vertical spacing between items in left column of highlighted (recent) posts section
• [ ] make TBA of links section sticky
• [ ] take inspiration from Github Blog and make more dedicated sections based on series?
• [ ] lazy load posts. Consider disabling prerendering