nx_ecomat_trend_gate.nx

nx_ecomat_trend_gate.nx -- executable proof for the advancement/expansion decomposition. NON-VACUITY IS THE POINT. T7 and T8 run the SAME code path over two fixtures that differ only in whether the domain count moved. If the instrument were stuck reporting RISING (the flattering answer) T8 fails; if it were stuck reporting FLAT, T7 fails. A gauge that cannot return both answers is not measuring anything, so the pair is the neg-control, not decoration. Fixtures are in-memory string literals: the core is pure, so this gate touches no filesystem and cannot pass by reading a stale artifact it wrote itself. Inherits the nx_gate_verdict base class (D001 DRY: gv_ctr/gv_head/gv_check/gv_verdict). license_tier: ORIGINAL No hw writes (Rule 26).