CDN-240: The Branch Resolution — Dual register validation on a twenty-five-cluster sample

CDN-240 validates the CDN-237 dual register on 25 clusters (12 original + 13 from LoCuSS/CLASH/CCCP). The refined κ-proxy converges with mean |Δκ|=0.041. P-class and E-class falsification predictions hold at 100%. Saturation tolerance tightens to ε_sat=0.068. Both branches score Strong. The dual register is declared valid as a two-track framework: Track A provides physical residual classification, Track B provides quantitative κ estimation. No tie to break.