Add lego brick/stud overlay mode

Similar to https://lego-art-remix.com/ 

<img width="868" height="875" alt="Image" src="https://github.com/user-attachments/assets/b09e4465-0cb2-480b-8060-d95df3874fea" />

or https://need.cafe/lego_art_generator/

<img width="1443" height="1445" alt="Image" src="https://github.com/user-attachments/assets/dad7b01e-8288-42d1-b440-be2b824a135b" />

