Thanks for the responses, everyone.  Violetta is alive and walking/clucking this morning, but won't eat or drink.  I tried scrambled eggs and blueberries, with a side of oatmeal ( a coop favorite).  I put vitamins in the water, but she isn't drinking. She is dripping serosanguinous fluid.  She layed her egg (soft, but no surprise due to the stress). 
 
Cheryl, I have some baby parrot food that can be mixed and fed by syringe.  Will that be the same idea as your critical care nutrition? I compared the label with the link you provided.  It looks similar, except the parrot food has a little more fiber.  I can mix it up to whatever consistency I want.  I have a tiny syringe for feeding, but no gavage tube.  I'm hoping I can get that at the feed store as well.  Maybe the pet store, as a last resort.
 
Happy Chooks, I plan to go to the feed store and get Pen G and some syringes.  There's no way she'll survive this without some antibiotics on board. I'm planning to clean the wound again with sterile saline wound spray, and figured I would do some type of wet-to-dry dressing, but have no idea how to keep it in place. 
 
Can I get vet wrap at the feed store, or do I have to get it from a pharmacy?  From my nursing/wound care days, I figure if I can keep the wound moist and clean, and she is being treated with antibiotics, she might have a chance.  (Of course, only if I can keep her hydrated.)
 
Cheryl, are you home?  Any chance you could help me hold her still for this initial cleaning and bandage session?  I have no idea how I'm going to do this alone.  Probably have to put a dark sock over her head to keep her still.
 
I went back in the coop and found a patch of skin (with downy feathers) that must have been what was torn from under her wing. Poor girl!!!