Voxy WorldGen

• fixed nether blocks rendering incorrectly in overworld after dimension switch
• fixed hard biome blend edges and snow artifacts on new world creation
• fixed generation continuing when voxy is disabled in its settings
• re-ingests chunks on load so voxy receives correct biome neighbor context
• discards LOD packets from mismatched dimensions to prevent cross-dimension rendering corruption
• pauses background generation worker when voxy rendering is turned off

This will be the last 1.21.6-1.21.11 update, everything will be 26.1+ from now on.