iMode dungeon structure export notes

Markers:
- Red wool: 2x2 connector group. Active connector groups must face-kiss all 4 red blocks.
- Pink wool: local floor reference marker.
- Blue wool: normal dungeon mob spawner marker. Suppressed in Sculk and boss rooms.
- Black wool: boss pending-spawn marker.
- Purple wool: in Steppes only, orientation seam marker. Lower purple top must kiss upper purple bottom; processor removes it. Elsewhere it may still become a Rite Focus.

Rules:
- Boss room is final and exactly one boss room is generated.
- Corrupted Knight bossroom weight: 70%; Samurai bossroom weight: 30%.
- All normal non-sculk/non-boss rooms have equal selection weight.
- Sculk is rare tier.
- Parkour is for going up.
- Garden behaves like maze: same-level connector hall.
- Steppes is a tall two-part room: dg_lowersteppes_nswe + dg_uppersteppes_nswe. The generator places upper exactly +22 Y above lower. All Steppes red connectors can be used as entrance or exit, but Steppes is never selected as an extra dead-end branch.
- Dungeons cannot place below the protected world bottom/bedrock layer, and clearing never removes bedrock.

- Boss rooms suppress vanilla natural mob spawns. Samurai pending boss spawn plays a 3-second cherry particle curtain before appearing.
