Sorry for your circumstances. Like everyone else said,bread,fruit,and vegetables would be good for her.
Make sure she gets water.How do you keep her from escaping when you set her down?I would love to see a picture of her(it could help us identify her breed)!and…
So sorry about your dog. It does sound like this chicken came to you at exactly the right time.
Everyone's got great ideas of what to feed her. If you are able to get to a farm store and tell them your predicament, they may have a broken bag of chicken feed they'd be willing to give you some of.
If you're near a feed mill or can get to one, tell them your dilemma, and maybe they'd give you a lb or so of some chicken feed for her. All of the table scraps ideas are great but she probably is lacking the nutrients she needs especially while still growing. If you could actually be choosy, an all-flock type of crumbles would be the best as it sounds like she's young yet.