Use diffy-surf.gif for the directory image

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: shixish

package.json

@@ -58,6 +58,6 @@
     "skills": [
       "./skills"
     ],
-    "image": "https://raw.githubusercontent.com/diffbot/diffbot-pi/main/assets/preview.png"
+    "image": "https://www.diffbot.com/img/home/diffy-surf.gif"
   }
 }