Void‑Hollow Update‑Add a brand‑new underground dimension

Add an independent new dimension called Void‑Hollow. It is a huge, sunless underground world. 1. Void stone. The primary rock block of this dimension. You can mine it with an iron pickaxe or above. ​ 2. Glow root. Pale glowing vine that hangs down from the ceiling of caverns. ​ 3. Grey cap mushroom. Large dark‑grey giant mushroom growing on the cave ground. ​ 4. Crystal shard. Translucent mineral block scattered on cave walls. ​ 5. Hollow stag. Neutral mob. Large deer‑like creature with crystal antlers. It wanders on open cave ground. Drops crystal fragments. ​ 6. Shadow lurker. Hostile mob. It hides in dark corners and chases players. Drops shadow dust. ​ 7. Forgotten citadel. Huge ancient fortress structure. It spreads across massive underground caverns. Treasure chests contain rare loot. Why