Re-think starters folder

The point of the starters folder is to give consumers a quickstart they can download using [giget](https://github.com/unjs/giget).

The starters folder causes maintenance difficulties:

- They can't use pnpm catalogs so we have to bump dependency versions in them separately
- We have to manually run `pnpm --prep-for-release` before making any releases
- We have to manually run `pnpm --prep-for-dev` if we want to run these locally

Other framework libraries use CLI to do starters, not giget. That seems like a much more robust solution that likely has a lower maintenance burden.