I want to reuse this for unlabeled pet styles is why! (That's been the
immediate motivation for this refactor, but also I do just like that
it'll make support forms easier to build.)
Instead of hand-rolling HTML, this offers helpers like `f.field`, to
help ensure the HTML is consistent, and to keep the templates more
focused on the unique form elements.
Specifically, I'm going for a more-vertical layout, cuz I want to bring
PetState over to it, and the weird grid situation wasn't gonna fit the
big pose label radios.
If you check this box, it'll keep you in a mode where saving an alt
style redirects you to the *next* one that needs labeling, until
they're all done. Useful for big drops!