chore(PreviewTools): Include border prop (#1482)

New version of Playroom include a border with embed previews. This cause
an extra border in the current visualizations like:
<img width="875" height="343" alt="image"
src="https://github.com/user-attachments/assets/f7053d22-fd65-4f8c-8812-d47f92c9e257"
/>

We are going to manage this border from PreviewTools because also need
to present examples without border like:
<img width="901" height="485" alt="image"
src="https://github.com/user-attachments/assets/2ada11a1-ce01-4378-99db-75ab738b8c1e"
/>

Author: yceballost