nx_etg_byzantine_test.nx

nx_etg_byzantine_test.nx -- KAT for E2.5 Byzantine M-of-N agreement. Verifies: T1 Unanimous: 5 replicas all CONFIRMED, m=5 -> CONFIRMED. T2 Majority: 3 CONFIRMED + 2 FALSIFIED, m=3 -> CONFIRMED. T3 Bare-majority: 3 CONFIRMED + 2 FALSIFIED, m=2 -> CONFIRMED (lowest-id tie-break since FALSIFIED also has count >= 2). T4 Below threshold: 2 CONFIRMED + 3 different outcomes, m=3 -> NO_AGREEMENT. T5 All different: 5 distinct outcomes, m=2 -> NO_AGREEMENT. T6 Tie-break determinism: 2 CONFIRMED + 2 FALSIFIED, m=2 -> CONFIRMED (lower outcome id) -- proves walk order. T7 N=0 -> NO_AGREEMENT. T8 m_required <= 0 -> NO_AGREEMENT. T9 m_required > n -> NO_AGREEMENT. T10 Counting helper exposes audit confidence: a 3-CONFIRMED- majority should report exactly count==3 when queried.