Flatten settings page into one scrolling page

The scrolling page should be flattened into one big scrolling page, with the tab control being replaced with regular buttons that jump to the appropriate section.

<img width="340" height="580" alt="Image" src="https://github.com/user-attachments/assets/a997ae4b-3aac-4445-949c-9c0ea5f60484" />
