Volta (Petras integer-order) — dx/dt=−x−a·y−y·z, dy/dt=−y−b·x−x·z, dz/dt=c·z+x·y+1. Classic a=5 b=85 c=0.5. Compact a=19 b=11 c=0.5. Distinct from chen.html, lorenz.html, qi.html, chua.html. RK4 strange attractor. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.