Add lobby/game worlds, void generator, dbd reload, and fix plugin loading

- Add VoidWorldGenerator for empty void worlds
- Add LobbyManager with auto-creation of lobby world (stone platform 7x7, built once) and game world
- Add /dbd reload command to reload all configs at runtime
- Add plugin.yml for proper command registration, remove paper-plugin.yml
- Fix mdbdBootstrap/mdbdLoader public constructors (Paper requirement)
- Fix command registration (getCommand null on Paper plugin system)

src/main/java/dev/loki/util/ParticleUtil.java

@@ -80,7 +80,7 @@ public final class ParticleUtil {
 
     public static void blood(Location loc) {
         World w = loc.getWorld(); if (w == null) return;
-        w.spawnParticle(Particle.BLOCK_CRUMBLE, loc, 20, 0.2, 0.2, 0.2, 0,
+        w.spawnParticle(Particle.BLOCK, loc, 20, 0.2, 0.2, 0.2, 0,
             org.bukkit.Material.REDSTONE_BLOCK.createBlockData());
     }