IV.T182 — Axial Coupling g_A from CF Window Algebra at 5.5 ppm

g_A = (1−ι_τ)²/ι_τ · (1+(8/17)α) = κ_D²/ι_τ · (1+(8/W₃(3))α) = 1.27637 at +5.5 ppm from PDG 1.2764±0.0006. Tree: κ_D²/ι_τ = 1.27123 (D-sector self-coupling at depth 2, projected onto master constant). NLO: (8/17)α where 8=|self-couplings|+|cross-couplings|=4+4, 17=W₃(3)=a₃+a₄+a₅. Crown of ch69 derivation chain.