Can a wife stipulate in her nikah contract that she is entitled to a divorce if her husband is abusive?

Yes, she can.

Now, on the counter to that, the term abuse needs to be defined.

Because unfortunately what's happened is that the ideas of abuse and trauma and other real terms have taken on a popular meaning, which is different than the legal meeting.

And so it needs to be defined what that would mean.

Is it abuse if your husband says, I'm not gonna talk to you for the rest of the day.

Or are we talking about physical abuse?

It's always important to define things, to minimize dispute and to maximize the benefit of why you're mentioning that thing to begin with.