Shadow Fog Effect for EtBW2

Adjust the background music for the Shadow Sun event to a fixed BGM (exclusive BGM can be turned off, set to minecraft vanilla BGM) 调整暗影之日事件期间的BGM固定为专属BGM，可通过配置关闭专属BGM改为原版BGM） Try to be compatible with Born in Chaos mod. Modify the spawn rules for the **Nightmare Stalker** from **Born in Chaos**: it now spawns exclusively during the **Shadow Sun** event at **noon**, at a random location within a **100–200 block radius** around the player, with a spawn cap of **one** per event. 尝试兼容《生于混沌》模组，魔改梦魇循踪兽的生成规则，仅会在每次发生暗影之日事件的正午时分（6000 tick）在玩家周围半径100-200格之间随机位置生成一只。 Adjust the armor configuration mode: it now uses **Armor Set IDs** from the **Armors API**. 护甲配置模式改用「护甲组合API」配置的护甲表ID进行设置。