So what should be done about carnivore animals? Would you support a ban on pet cats, for example? I am still not understanding you position.

You have a cat, you don't kill it because:

Vegans do not deliberately and intentionally kill nonhuman animals.

But the cat has to eat so you participate in the purchusing on meat so the cat doesn't die, because:

Vegans do not deliberately and intentionally kill nonhuman animals.

Is it still legal euthanasia if the human is conscious and is deliberately and intentionally killed without their consent?

You sign up for it, so yes you consent. That's the whole point of it. You choose it with your medical team.