Certified critical-line bound 0.673638876665040004721950996645

Contribution by Kristian Muri Knausgård. Derived from Bei Yi's beiyi-ten-d250-t022 (2026-11-09), building on Rishi Khan's TEN certificate, Samuel Lavery's agent team's OpethN/am-cert/bridge-port, R. Arun Chandru's master-of-puppets series, Yuhang Shi's refinements, ajp88's window work, the Zeta Lab bridge, Anthropic's Zeta23 library and Knausgård's Lean developments for arXiv:2609.33043 and arXiv:2610.08965. Carries over the terminal H_W enclosure from knausgard-ten-hw50-order36: AMW.taylorN_F uses Complex.exp_bound with n := 36; the rational bounds for sqrt(2)/2, cos(sqrt(2)/2), sin(sqrt(2)/2) and the H_W floor use denominator 10^50 instead of 10^42. The improved floor is propagated to the final exact bound. Window coefficients, certificate data, tree, root cover and certificate checker are unchanged. Upstream copyright, license and attribution notices are retained.