Save Daisy: A Starving and Sick Cat

This is a cat I call Daisy. She has come to my house for months now. I first caught her in a cat trap, but when we put out a notice saying this is someone's cat, clearly by the collar, they messaged my girlfriend saying this cat is an indoor-outdoor cat and told us to just let her go and she'll come home. So we let her go free, and that was that.

Fast forward to now, where for multiple weeks, this cat has slept in this box made for homeless cats. Clearly, she is starving and suffering from illness as well as fleas from being left out in the elements of the Central California winter. I've been feeding her and making her stay on my front porch better, but this cat is someone's pet and is so sweet and doesn't deserve to suffer. She doesn't have the survival skills of wild cats. I would have taken her to the vet if I had the money to do so, but unfortunately, I do not. Please, if you could donate so I can get this cat the help she needs, she can finally be healthy and I can finally take her into my house where she'll be taken care of, unlike whoever her "owner" is.

(I DON'T WANT THIS CAT TO BE PUT DOWN BECAUSE OF SOMEONE BEING A SHIT OWNER)