- Fix sort(), incorrectly using the front Z channel in a place where it should have instead used Zback channel. - Widen pixel indices from int to int64_t (internal only, follow-up to #2363). - Cleanup unreachable branches in merge_overlaps(). Modified the `DeepData::sort` test to include samples with a tied front Z, so it verifies the Zback fallback. Signed-off-by: Luna Kim <177369799+luna-y-kim@users.noreply.github.com>