docs(readme): add HOL Guard verified badge (#509)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: TMHSDigital

README.md

@@ -1,5 +1,7 @@
 <h1 align="center">Blender Developer Tools</h1>
 
+[![HOL Guard](https://img.shields.io/endpoint?url=https%3A%2F%2Fhol.org%2Fapi%2Fregistry%2Fbadges%2Fplugin%3Fslug%3Dtmhsdigital%252Fblender-developer-tools%26metric%3Drelease)](https://hol.org/registry/plugins/tmhsdigital%2Fblender-developer-tools)
+
 ---
 
 <p align="center">