Save Shopping List Mapping ingredient -> Category

When I put items into my shopping list they are not always assigned to the correct category (or the one I want). Now we can reassign items to another category. But it would be helpful if this reassignment is safed for later as well. So if I put the same item (from the same recipe) into the shopping list, it is assigned the category I chose before.

That would also require the custom categories to be persistent (I think currently they are deleted when the last item is removed from the category).