Hi, sorry it's been so long. Right, if a kitten (or cat for that matter) is denied access to a room or cupboard that space becomes a bit more important. As you've already said she is a little bit naughty and wants to rule the house, so it is important to her that she can get everywhere
Some cats aren't bothered and do their own thing, however your little kitty sounds very curious.
You could try some of the repellent sprays that are on the market and spray the carpet outside the door, but in my experience they either don't work or you have to be doing it too often
I'm afraid the best way is just to let her get on with it, don't make a fuss of what she's doing, but check to see where she goes afterwards and just put the stuff back. By not making a fuss she may grow out of it or become bored. If you do make a fuss she might think it's a game and do it all the time
I know this isn't what you hoped for, but this way, I think, is your best shot. Good luck
