Shimizu–Morioka — dx/dt = y, dy/dt = x − a·y − x·z, dz/dt = −b·z + x². Classic a=0.75 b=0.45. Dual a+b sliders. Distinct from anishchenko.html, vallis.html, sakarya.html, pehlivan.html. Bulk centroid ≈ (0.0029, 0.0012, 0.9525). RK4 Shimizu fold. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.