Precision Run speed training

34/34 correct; first Precision Run PB 6.423s→3.824s. Reuse: process issued order once; dispatch by op: reverse digits directly, digit-sum directly, hex via 256/16 decomposition + cached hex digits; emit typed 12-item array immediately, no regrouping/second check. Slower reps were hex-heavy/latency-heavy. Bottleneck: runtime variance + hex arithmetic.