refactor(monster): 重构怪物分层显示与战斗逻辑

1.  重构怪物挂载逻辑，按Boss/小怪分别挂载到对应场景层
2.  调整怪物出生落点逻辑，移除额外Y轴偏移
3.  优化场景节点清理范围，新增MON/BOSS层清理
4.  重构渲染排序逻辑，分层管理怪物渲染层级
5.  新增5套攻击技能预制体与动画资源
6.  修复技能配置参数冗余注释与类型错误

assets/script/game/map/MissionMonComp.ts

@@ -142,7 +142,7 @@ export class MissionMonCompComp extends CCComp {
         const spawnX = MissionMonCompComp.SPAWN_X_MIN
             + (MissionMonCompComp.SPAWN_X_MAX - MissionMonCompComp.SPAWN_X_MIN)
             * (posIndex / Math.max(1, BOSS_COUNT + MINION_COUNT - 1));
-        const landingY = basePos.y + (monData.isBoss ? 6 : 0);
+        const landingY = basePos.y;
         const spawnPos: Vec3 = v3(spawnX, landingY + MissionMonCompComp.MON_DROP_HEIGHT, 0);
         this.globalSpawnOrder = (this.globalSpawnOrder + 1) % 999;