nx_clean_market.nx

nx_clean_market.nx -- LIB: the FULL clean-produce MARKET in TWO HONEST TIERS (R-IMPACT-4). Extends the impact catalog to the complete Dirty Dozen (12) PLUS a Clean Fifteen set, and -- this is the point -- proves we MEASURE honestly rather than cherry-pick scary produce: Clean Fifteen crops are genuinely low-residue even conventionally, so their clean GAP is SMALL. We show them anyway, labelled as such. Every item still triple- wins (cleaner + greener + cheaper + higher-margin), but the clean-gap CONTRAST by tier (large for dirty, small for clean) is a falsifiable anti-greenwash property the gate checks. Reuses the existing 8 Dirty-Dozen records (owned by nx_produce) via the tier index; adds 4 dirty + 5 clean. Integer cents (no float). Each record CITEs the regenerative-agriculture corpus; relative rankings follow the published lists. license_tier: ORIGINAL