aho: Question mark clues do not validate shape

[Lennard Sprong]

We should check if existing aho puzzles make use of this problem before fixing this.

[Martin Ender]

There don't seem to be any vanilla Ahos in the DB that use question mark clues. The only one I can see is this variant Aho, which (judging by the rules explanation on the blog) expects question mark clues to work as intended, not as currently implemented: https://ihnnpuzzles.blogspot.com/2020/12/puzzle-272-filling-space-aho-fillomino.html