Restyle docs site to match pacperlar.online design language

Link the GitHub Pages docs site from the README

Add GitHub Pages docs site: server + Lua plugin reference

Cave generation, singleplayer villagers removed (server-only now)

Crafting panel, furnaces and iron tools

Launcher: mirror picker with region-based recommendation

Launcher: GitVerse mirror fallback

Villager NPCs and the pickaxe

Water and lava with flowing physics

Windows: fetch LuaJ in get-deps.bat, fail build.bat on javac errors

Relicense new versions under Apache 2.0

Remove stray pid files, ignore *.pid