Add stone variants, sky structures and Sky‑Citizen NPCs

I suggest adding a brand‑new sky‑themed update. Generate large floating islands at Y=200‑280 across the overworld. Spawn grand sky structures upon these islands, including ruined sky castles, aerial monasteries and floating dungeons filled with traps, puzzles and valuable loot. Add the powerful Sky‑Lord boss which spawns inside these major sky structures. The Sky‑Lord can launch shock‑wave attacks, levitate freely and summon phantoms to fight alongside it. Defeating it can grant unique sky‑themed loot and gear. Besides sky‑related content, please also complete decorative variants for all existing wood types. Add chiseled wood blocks, wooden pillars and corresponding wooden trapdoors for every wood set. These materials are perfect for constructing sky‑bridges, timber‑style floating houses and sky settlements. This update can enrich high‑altitude survival exploration and give more building choices for sky‑themed builds. Thank you for reading this