IV.P222 — m_u/m_d Isospin Ratio from Winding Algebra at +82 ppm

m_u(direct)/m_d(chain) = 2.161/4.698 = 0.4600 at +82 ppm from PDG 0.4596. Consistent with NLO scan +29 ppm but derived from β_u=11/2 rather than scan-based formula. Isospin splitting from T² eigenvalue asymmetry λ(0,1)/λ(1,0) = ι_τ⁻².