The new major version of Storybook is better in many ways, and the

migration isn't too hard. This change updates us to use it.
For the most part, this is just swapping out old versions for new, and

removing some packages that have been consolidated. Actual changes

include:

We no longer need to manually inject axe-playwright into the page,

  since the a11y tests are now handled automatically.
Fixed the text-color assignment in theme.css, since there's actually

  nothing called --ink-p-text-color.
Pinned the version of @types/react because @types/mdx uses older

  names for things even when @mdx/react seems fine.

Ran full installs and builds.
Ran build-storybook
Ran the storybook server and flipped through various components.

  Verified that things worked as expected.