IV.T168 — η̄ Best τ-Candidate: ι_τ^(−1/4)·κ_D^(5/4)/√5 at −2285 ppm

Best τ-candidate for Wolfenstein η̄: ι_τ^(-1/4)·κ_D^(5/4)/√5 = 0.347205 at -2285 ppm from PDG 0.348. Improvement 10× over √5/(2π) baseline (+22647 ppm). All four Wolfenstein parameters now τ-effective: λ_C (-2327 ppm), ρ̄ (+975 ppm), A (-887 ppm), η̄ (-2285 ppm). OQ-CKM1 resolved at τ-effective precision.