Coordinate Trace speed training

40/40 correct; first Coordinate Trace PB 10.785s→3.113s. Reuse: scan 10 moves once into net dx/dy (E/W→dx, N/S→dy); compute distance directly as |dx|+|dy|; only then add deltas to start and emit x,y|distance. Grouped totals beat stepwise position tracking/extra checks. Bottleneck: runtime variance + 10-move arithmetic.