Okay at first I was confused and thought you were being rude by giving someone you knew was a vegan a cheesecake and meat sandwich. Thanks for the clarification. I'm vegan btw and I was actually seeing red on her behalf, thinking this was the case!
But given your update, I totally see why you would have thought it appropriate - her actions told you she was perfectly okay with- and even liked - the cheesecake and meat. I say you did nothing rude, and yes, she was rude for assuming it's your responsibility to ensure she stays vegan. It's not, it's hers.
If she's thinking of being more committed, she should've said something before you gave her the cheesecake (like you do every year, so no surprise there) and she still should have thanked you for ALL of the gifts.
She sounds a bit flaky, I wouldn't worry about it. You did nothing wrong.
Don't be surprised, though if you get her family nuts next year and they gripe how everyone else got a cheesecake,