Stray "Hello World"

The string "Hello World" appears in four different places in the codebase. I assume they were added as a placeholders and should be removed/replaced. Example:

<img width="590" height="597" alt="Image" src="https://github.com/user-attachments/assets/4fabd0ab-0c27-45cc-9ed7-156a7f6074b7" />