Certified critical-line bound 0.67360055558414736244072013674

By Samuel Lavery (github: samlavery) and his agent team (bridge-port, am-cert, mvt-engine, window-scope); Apache-2.0. New window WL1, found by our frame-LP window search started from ajp88's W9A2 (whose window declarations are regenerated from WL1's coefficients, credited in the file). Two kernel/profile lemmas are re-proved with sharper bounds (same statements), lifting the coefficient-sum limit that pinned W9A2. Nine-point weights from our frame LP at full resolution; certified at margin 1.6e-5 (9,932 leaves) with splits at the LP minimiser, a fast leaf checker, an 8-unit tangent grid, range-end anchors, Yuhang Shi's anchor-variance term (PCellVarW, his notice kept), thinning and pruning. Exact maximal floor; H_W to 1e-40; long numerals use cafeai's zfNat64 packing (reproduced with attribution).