CDN-344: The Population Prior Closure Test - Art Edition

CDN-344 propagates the CDN-343 lognormal concentration prior through the full 20-lens SLACS contracted Channel B ledger. Using c0=10.0 and sigma_log10(c)=0.15 dex, the paper distinguishes coherent single-c closure from independent lens-by-lens concentration draws. Coherent full-sample closure remains a 21.2% upper-tail event at c>=13.174, but independent BE draws yield expected pass count 17.67/20, P(20/20)=3.5%, and P(>=19/20)=24.0%. The simple-MOND boost raises P(20/20) to 6.7% but does not remove the population-level tension. Verdict: POPULATION_PRIOR_CLOSURE_STRAINED.