IV.R413 — OQ-C7 Status: PARTIAL-IMPROVED after Sprint 7C

OQ-C7 PARTIAL-IMPROVED: θ₂₃ at +8604 ppm (from +18012), θ₁₂ at +3106 ppm (from −84888), δ_CP at +9365 ppm (new). θ₁₃ at +136k ppm remains hardest. θ₁₂ approaches τ-effective (<1%). Full structural PMNS derivation from 3-gen winding basis.