Nice! My mom has a small tree like that. She keeps it out all year and decorates it according to the season or holiday.May I suggest an artificial small tree like a fake birch tree? It would make the decorations higher and the way the branches are would prevent cats to jump in it. It's not as impressive looking as a regular Christmas tree but it keeps the spirit and you can still used the same decorations in them. And if you like it, you can just remove the decorations and keep it out all read round without seeming out of season!
Here is a picture of what I mean:
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I wish you the best of luck with your kitty dilemma!