V.P123 — PMNS Mixing Angle Prediction

PMNS mixing angles from sigma-polarity eigenvectors. Wave 11A status: θ₂₃ at +8604 ppm via A-sector rotation (IV.T174), θ₁₂ at +3106 ppm via QLC fiber-base duality (IV.T175), θ₁₃ at +136k ppm (13.6% gap) — genuinely open frontier. A-sector mechanism (π-generator on base cycle) and fiber-base duality (quarks on T², leptons on τ¹) structurally established. θ₁₃ double-crossing amplitude explored but no viable formula found; flagged as open problem.