IV.R401 — Cross-Check: 1/21 in p-n Mass Difference = 1/(4·W₃(4)+1); n=7 Higgs at +8 ppm

Cross-check of NNLO Window pattern: 1/(4×W₃(4)+1) = 1/21 appears in p-n mass difference bonus formula (√3/2)·ι_τ⁶·(1+(1/21)·ι_τ²). Also: n=7 in Higgs formula gives +8.0 ppm from PDG 125.20 GeV (vs n=6 at +466 ppm), a new open question for the next sprint.