Rename image to match _featured_image convention

Rename 2026-04-07_feature_image.webp to 2026-04-07_featured_image.webp
and update the reference in index.md for consistency with other posts.

Author: mrbiggred

…2026/04/07/2026-04-07_feature_image.webp …026/04/07/2026-04-07_featured_image.webpdocs/posts/2026/04/07/2026-04-07_feature_image.webp renamed to docs/posts/2026/04/07/2026-04-07_featured_image.webp docs/posts/2026/04/07/2026-04-07_feature_image.webp renamed to docs/posts/2026/04/07/2026-04-07_featured_image.webp

@@ -20,4 +20,4 @@ Everyone and anyone are welcome to [join](https://weeklydevchat.com/join/) as lo
 
 *Image generated by Nano Banana*
 
-![Attempt to Run an LLM Locally](2026-04-07_feature_image.webp)
+![Attempt to Run an LLM Locally](2026-04-07_featured_image.webp)