[WIP] copy the mockup HTML to the repo.ts template

c8ec771f99269d0c7174b7e6cadb196821ff2074

Tucker McKnight <tmcknight@instructure.com> | Sat Jul 11 2026

[WIP] copy the mockup HTML to the repo.ts template

This is the start of implementing the new-header-area.html design
that's in ui-experiments.