V.T167 — Effective Majorana Mass from sigma-matrix

The Majorana effective mass = |sum_i U_ei^2 * m_i| computed from the sigma-polarity mass matrix (V.D233) with Sprint-3 best-fit (p=3.7, q=4.8, r=2.8). Central value ~ 19 meV (Sigma_m_nu = 89 meV, normalized). Uncertainty band (pm0.5 on each p,q,r): [9, 31] meV. Consistent with KamLAND-Zen (<36-156 meV, 90% CL) and GERDA (<100-190 meV). Within LEGEND-1000 sensitivity (~10 meV). NOTE: Uses naive PMNS from sigma-matrix eigenvectors; full flavor-basis rotation gives different angles (theta_12, theta_23 wrong). Quantitative prediction pending Sprint 5 (PMNS derivation).