Implement Moon ARG core systems (Blood Moon, entities, portal trigger)

[Copilot]

The mod needs an initial functional Java implementation for the Moon ARG GDD: core init, Blood Moon mechanics, animal paralysis, custom entities, and Moon portal entry. This PR wires the foundational gameplay systems for Fabric 1.20.1.

• Initialization & registries
  • Added mod entrypoints and registries for blocks, fluids, items, and entities.
• Blood Moon mechanics
  • Client moon-stare tracking + server state management and time-slowdown mixin.
• Entity behaviors
  • Moonman Weeping Angel AI + Moon teleport on touch, Stalker edge spawn/despawn, Glitch block deformation on spawn/despawn.
• Portal trigger
  • Nether portal + “Moon is god” book item detection to teleport players into the Moon dimension.

Example (Blood Moon time slowdown mixin):

@Redirect(method = "tickTime", at = @At(value = "INVOKE", target = "Lnet/minecraft/world/WorldProperties;setTimeOfDay(J)V"))
private void moonarg$slowTimeOfDay(WorldProperties properties, long timeOfDay) {
    ServerWorld world = (ServerWorld) (Object) this;
    if (BloodMoonManager.isBloodMoon(world) && world.getTime() % 2L == 0L) {
        properties.setTimeOfDay(timeOfDay - 1L);
    } else {
        properties.setTimeOfDay(timeOfDay);
    }
}