Finding 1: strip trailing [digits] array-element suffix from Signal so one
calibration entry covers an entire array signal, matching the C++ strchr
truncation and the JS equivalent.
Finding 2: after the 16-byte Unit truncation, drop any trailing partial UTF-8
rune so json.Marshal never emits replacement characters; keeps byte limit in
sync with C++ strncpy(u, unit, kMaxUnitLen).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
