nx_procgen_features.nx

nx_procgen_features.nx -- feature KINDS assigned by biome law (PROCGEN arc P3 = EXCEED10 ladder R2; seeds bucket B6 structures). The grader's FEATURE_VARIETY axis (Shannon entropy over a kind histogram) was structurally ABSENT (=0): the landscape's poisson points had positions but no KINDS. This module gives each feature a kind the causal way -- the biome it stands in decides what can grow there, and a seeded jitter stream picks within the biome's mix: TREE -- forests dominant; grassland scatter; treeline thins them ROCK -- deserts, tundra, snowfields, ice; outcrops elsewhere SHRUB -- the understory mix everywhere green WATER -- rare: oasis (desert), melt pond (tundra), swamp pool (tropical) -- placed where water causally collects The mix table is the law (build-intelligence cardinal: a biome with bad features gets a BETTER mix row, never a stripped one). No TREE in DESERT is a tested invariant, not a comment. Deterministic per (features, biome_map, seed): byte-identical kinds. license_tier: ORIGINAL