perf: convert blog article image from png to webp

Author: jderochervlk

_blogposts/2025-11-04-reforging-build-system.mdx

@@ -1,8 +1,8 @@
 ---
 author: rescript-team
 date: "2025-11-04"
-previewImg: /static/blog/rescript-12-reforging-build-system.png
-articleImg: /static/blog/rescript-12-reforging-build-system.png
+previewImg: /static/blog/rescript-12-reforging-build-system.webp
+articleImg: /static/blog/rescript-12-reforging-build-system.webp
 badge: roadmap
 title: "Reforging the ReScript Build System"
 description: |