Well, not the news I was hoping for with skeleton kitty. Took her to the vet again last week for more tests, as she just didn't seem to be improving like I thought she should be - had gained a pound and a half (up from 6 pounds on her first visit a month earlier) but was still super skinny. Blood tests showed she's in kidney failure, which, unfortunately, is not something that tends to get better, although some cats can live months or years with the condition.
She seems happy if a little low energy, and isn't in pain from that condition, although she seems to have something going on with her back legs - vet suspected old fractures, although kitty is SUPER uncooperative, had to be wrapped up like a burrito for any sort of exam (and by the fight she put up this is not a kitty on her last gasp by any means!). Decided not to put her through stress of X-rays. She doesn't like having her back half messed with, but as far as I can tell it's not causing her undue distress.
So, adoption by anyone is unlikely, athough a few of my Facebook peeps (and mom, who is the softest softy there ever was) sent donations to help cover expenses, which was utterly sweet of them and very much appreciated. She seems content living in my bedroom for now, just planning to provide supportive care and diet and see how she does, and try to make the best decisions based on her quality of life. She stopped eating for a few days, possibly because of the antibiotics the vet put her on? But now that she's been off them her appetite has been gradually picking back up, and she's loud-mouthed and purry and demanding as ever.