Hare's strings::compare returns int (ref/hare/strings/compare.ha:12).
Result is a sign, not an index, so the i32 was cargo-culted from the
str-index type. Callsites already compared against 0, so callers
needed no migration. Widened the two return-site casts (u8→int,
i32→int) — the latter avoids i32 underflow on adversarial length
diffs. Added a multibyte test row contrasting ASCII vs UTF-8 lead
byte to exercise the high-bit-operand path.