Convert the Redundancy pool

BUR #58916 is pending approval.

convert pool:2181 -> redundancy

I feel like this is taggable as a concept, but this will require some cleanup
For example, the current description states to not add a post if it "...can be covered by recursion (e.g., stacking bottles) or name connection (e.g. Mustang (character) + Mustang (car)).", yet we have several results for pool:Redundancy *_(umamusume) *_(racehorse)

It's not clear to me what the difference between this and recursion would be. It seems like a large overlap.

I assumed that recursion is used for something that repeats itself in a seemingly endless manner (i.e. the Droste effect), like post #10838448, while redundancy is for something like "it already has x, and now you're adding x again on top of it" without the endless repetition. In post #9335736, Orin is already a cat girl, having her do the cat shadow puppet is redundant

It doesn't seem that similar to me. Recursion is mostly a visual tag about a visual recursion occuring: An image in an image repeating, repeated reflections etc, while redundancy is much more of a conceptual tag of characters doing something completely redundant.
I can see both tags applying to pictures like post #8891565 and post #9967232 but recursion doesn't seem right for the self cosplay jokes like post #8365564 or something like post #6584611 and similarly I don't think redundancy would apply to a lot of recursion posts like post #9989544.

Yeah, recursion is an artistic technique, while redundancy is moreso a theme that can be applied to a post I feel like.