Certified critical-line bound 0.673548002957895184345917669536

Refines the accepted master-of-puppets3 proof by retaining the positive two-anchor variance term in its supporting-parabola bounds. Six previously certified curvature intervals give a uniform correction to the exact leaf checker, increasing the eight-point certificate floor from 80872002/10^10 to 80872074/10^10. The window coefficients, packed certificate data, cover geometry, pressure and analytic counting chain are unchanged. The terminal HW floor is sharpened to 672168410564118872522651/10^24. All inherited attribution and license notices are retained. No new numerical optimization or interval search is used. The proof exports both the fixed dyadic and cumulative distinct-critical-line counting bounds.