nx_assetvariant_gate.nx

nx_assetvariant_gate.nx -- prove SWAP-AS-DATA v0: ONE part-recipe system emits MANY distinct creature/person variants by swapping slots (species x head x ears x tail x build), all rendered on the SAME photoreal-path shader into a 4x3 CONTACT SHEET (the DnD bestiary card). Asserts: T1 every variant visibly renders (foreground coverage per tile) T2 all 12 variant tiles are pairwise DISTINCT (diversity is real, not one blob) T3 a HEAD-SLOT-ONLY swap changes the render (plain vs horns on the same base = the swap works) T4 species swap changes the render (human vs wolf) Writes knowledge/synth_variants.png (384x216 sheet). license_tier: ORIGINAL expect_exit: 0