The and/or/xor operations round both masks to 0 or 1 before combining,
so they discard feathering. There was previously no way to take the
union or intersection of two soft masks without losing intermediate
values. max and min are the standard fuzzy-set equivalents and preserve
them.
Also documents on the operation widget which ops are arithmetic and
which binarize, since the distinction is not visible from the names.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>