STABBACK Monster Defense Attack

### Is your feature request related to a problem? Please describe.

Ankylosaurids had a bunch of spikes so if you decided to bite one, you would enjoy a mouthful of piercing damage, so much so that you would probably stop before you even hurt it. Also they might break off your teeth. We have ZAPBACK and ACIDSPLASH that are kind of similar.

### Solution you would like.

ZAPBACK but cutting damage and no stun. Ideally it would only trigger if you don't have a reach attack, and would trigger a lot if you're just like punching it. I could imagine a use for this in main game too, basically a hedgehog zombie evolution. Ideally it goes away when the monster is knocked over.

### Describe alternatives you have considered.

N/A

### Additional context

"It would have certainly been off-putting for predators to bite down on an animal covered in sharp spines like these" from https://gizmodo.com/these-spikes-grew-right-out-of-a-dinosaurs-ribs-1847741722

Start by locating the existing ZAPBACK and ACIDSPLASH implementations and compare how their triggers, damage, stun, reach-attack handling, and knockdown behavior work. The feature is done when an ankylosaurid-style defense deals cutting damage without stun, favors close attacks, and is removed when the monster is knocked over; clarify the intended main-game scope first.

Written by the indexing model from the issue text.