nx_dr_drbench_gate.nx

nx_dr_drbench_gate.nx -- KAT + neg-control for the DRBench+DEER scorer (DR-0). Proves every metric's integer math (insight-recall, distractor-avoidance, factuality, request-completeness, evidence-validity, overall mean) + empty-guards + the NEG-CONTROL that encodes DRBench's central finding: a report with perfect distractor avoidance but ZERO insight recall must NOT beat a good report -- insight recall (the binding constraint) distinguishes them, so the composite is not gameable by avoidance alone. DRY nx_gate_verdict lib (D001 migrate-on-touch).