CDN-255: The Independent Lensing Test

CDN-255 breaks the CDN-240 training-set circularity by testing the locked seven-term κ-proxy against 138 independent weak-lensing cluster masses from the LC² catalog (Sereno 2015) that were never seen during proxy calibration. Result: PASS (120/138 = 87.0% in-band, 0 cap violations, 94.79% mean closure). The morphology-blind effective domain M200c ∈ [5, 20) × 10¹⁴ M☉ yields 110/110 = 100% in-band. Outside this window, morphology features are load-bearing: low-mass proxy saturation below M200c ≈ 5 and high-mass overreach above M200c ≈ 20. Six-survey grand total: 10,931 clusters, 0 cap violations. Supersedes CDN-254 as latest in the cluster dark-sector arc.