The New Review Request page now works in both light and dark modes. Much

of this is pretty straight-forward, moving to standard Ink design tokens

for headers, links, borders, and data tables (for the commits).
The one larger change is that the error information now uses Ink Alerts.

This gives a more consistent error appearance, and a more prominent

button for "Try again."

Tested the page in light and dark modes.
Tested repositories with and without post-commit support.
Tested with branch and commit errors.
Tested diff upload errors.
Tested commits already posted for review.
Unit tests pass.