rel_delta caps one message at +-63 (7-bit offset-64); firmware acceleration
compresses a fast flick to 1-2 messages, so flick-to-max landed at ~125.
A saturated delta in the end-stop band (>=115 up / <=12 down) now snaps to
127/0 — slow turns never saturate, precise control untouched. Feel bands,
PLN vetoes at rehearsal.