fix(hero): 修复BOSS怪物层级显示问题

当怪物为BOSS类型时，设置其节点层级为BOSS专用层级，确保BOSS显示在正确层级

assets/script/game/hero/Mon.ts

@@ -69,6 +69,7 @@ export class Monster extends ecs.Entity {
         model.type = hero.type;
         model.fac = FacSet.MON;
         model.is_boss = monType == MonType.BOSS;
+        if(model.is_boss) node.setSiblingIndex(IndexSet.BOSS);
         if(!model.is_boss){
             model.is_kalami = true;
         }