I'd try placing her in the temporary run and see how it goes.
Likely the first thing she'll do is take a dust bath, so it's important you determine if the wound is scabbed/healed over well enough to withstand all that movement.
Yes. I have experience with wounds and dust bathing, it can be a mess

I would try playpen/look don't touch re-integration. You do want that wound healed and hopefully she will feather back in too. It takes time and patience for large wounds like that to heal.
Hard to know if the other hen was pursuing her so vigilantly because of the wound, maggots...I still really think that looks like a Flystrike wound, so the other hen may have actually been after the maggots and that's why you didn't find any, but it's just a guess on my part.
You never know how things will work out with introductions, sometimes things go smoothly, other times you don't. I'm not necessarily one that can give great integration suggestions
@azygous may be better at that! Most all my hens seem to be brawlers and always have been. One breed I keep, I have to monitor hens closely since they are prone to get really testy, so I tend to let them fight it out more than what most would I suppose. Of course, I monitor closely and separate/break up things if it's going too far south, but hens can be quite brutal to one another.