I have a chocolate Mickey and Minnie Mouse in my glass cabinet for many years now. They are both in some plastic packaging (the kind they also put around gift baskets), in a glass cabinet but not in an air conditioned place.
After all these years, they are not molded.
I have kept a chocolate bunny for many many many many years like that, it wasn't wrapped, and I had put it on a piece of cardboard, since the oil in the chocolate tends to come to the surface, and I didn't want to stain my shelves. It fell apart when I tried to move it, it had dried out completely.
My dad has kept a chocolate steam train for 10+ years.
As someone suggested: get a glass dome, but it on something flat, glass dome over it, and once it gets that dried out look, don't move it too much!
This should work just fine (and this comes from someone from chocolate country)