nx_procgen_signature_test.nx

nx_procgen_signature_test.nx -- KATs for the P1 composed-primitives signature features. Exit 0 = all pass; first failing KAT's number is the exit code (loud, names the failure). KAT 1 peak apex: center cell rises by exactly amp (d2=0 term). KAT 2 peak reach: a cell beyond radius is untouched. KAT 3 ridge symmetry: cells mirrored across the segment move equally. KAT 4 valley is ridge negated: same geometry, opposite sign. KAT 5 cliff is antisymmetric: left side up, right side down. KAT 6 compose determinism: same (seed,preset) twice -> identical maps. KAT 7 compose moves EXTREMES: graded ext after >= before on the same fbm base (the P1 gate axis, proven at module level). license_tier: ORIGINAL