Add custom blog header for announcement

Author: SimonDarksideJ

website/content/blog/2025-12-30-385-new-sponsor-announcement.md

@@ -4,8 +4,8 @@ date: "2025-12-30"
 excerpt: "ConcernedApe invests in MonoGame's future, joining the other Premier Sponsors"
 tags: announcements
 author: MonoGame Foundation
-image: /images/blog/cover/monogame_foundation.png
-ogImage: /images/blog/cover/monogame_foundation.png
+image: /blog/images/2025-12-30/blog_header_ca.png
+ogImage: /blog/images/2025-12-30/blog_header_ca.png
 ---
 
 ![New Sponsor Announcement](images/ConcernedApe.webp)