v2: parser_v5 IR (regions, spike dirs, on/off footprints, entity names), legend v2 (boss door D), boss-entity mmm_boss config, +48K levels, official author-disjoint splits, ~25 new columns

Initial release: 179,166 MMM levels with ASCII grids, MarioGPT-style text prompts, IR JSON, thumbnails, and raw .mmlv bytes