PR #66 review round 2: the pairwise EqualFold loop was quadratic, 7s of CPU for ~90k keys under the 1 MiB body cap. foldKey maps each rune to the smallest member of its unicode.SimpleFold orbit, equal exactly when strings.EqualFold is, so the scan is a map lookup again. The scaling test fails on the previous code (7.1s). Refs #65 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>