Add directional arrow to decal entity boxes

I believe this will help in quickly finding where a decal is "projected" without having to change the values. 
Currently entity boxes are like this with no visual cue for the direction that is set: 

<img width="1081" height="894" alt="Image" src="https://github.com/user-attachments/assets/920f9e7b-6716-4f95-be61-8d2fa9ca4730" />

