The Discarded sidebar entry navigates to /photos?is_discarded=true, which
already excludes is_hidden=true rows (the cross-cutting hidden-folder
filter). The /library/stats discarded_count did not, so the badge could
disagree with the actual list — e.g. dtoro saw 1,281 in the badge but
only 25 in the view because the hidden Memories/ source root holds 1,256
discarded rows. Aligning the count with the view, like every other
sidebar badge already does.