V.T175 — Best sigma-Matrix Exponent Pair from Grid Scan: (Delta_pq=1.16, Delta_pr=0.87) at +7 ppm

Numerical result (tau-effective): The sigma-polarity mass ratio |Delta_m^2_31/Delta_m^2_21| = 32.58 (PDG) is matched to +7.4 ppm by exponent offsets (Delta_pq=1.16, Delta_pr=0.87) with r=2.8. Physical: p=r+0.87=3.67, q=r+0.87+1.16=4.83. Rational approx: Delta_pq = 29/25, Delta_pr = 87/100. This is a numerical tau-effective statement; structural derivation of why 1.16 and 0.87 remain open (OQ-C3).