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.
Most notable change here is extracting the pose option bubbles into a
`data-type="radio-grid"`, and pulling that into the `.support-form`
CSS. My rationale is that, unlike most fields, this field benefits from
being 100%-width, and I don't want to specify that as an override if I
can avoid it, because that's fragile-y.
Instead, I extract this into a generic type of field that
`.support-form` can use (it feels pretty reusable anyway!), and require
the caller to specify how many columns they want as `--num-columns`.
Oh right, yeah, we like to do things gracefully around here when
there's no corresponding color/species record yet!
Paying more attention to this, I'm thinking like… it could be a cool
idea to, in modeling, *create* the new color/species record, and just
not have all the attributes filled in yet? Especially now that we're
less dependent on attributes like `standard` to be set for correct
functioning.
But for now, we follow the same strategy we do elsewhere in the app: a
pet type can have `color_id` and `species_id` that don't correspond to
a real record, and we cover over that smoothly.
