적과 타워가 서로 공격하지 않는 문제 수정

Assets/Scripts/BuildingManager.cs

@@ -22,6 +22,10 @@ namespace Northbound
         private List<Building> placedBuildings = new List<Building>();
         private List<BuildingFoundation> placedFoundations = new List<BuildingFoundation>();
 
+        // Level 1 건물 캐시
+        private List<TowerData> _buildableBuildingsCache;
+        private bool _buildableCacheDirty = true;
+
         private void Awake()
         {
             if (Instance != null && Instance != this)
@@ -41,6 +45,26 @@ namespace Northbound
             );
         }
 
+        /// <summary>
+        /// 건설 가능한 건물 목록 반환 (Level 1만, 캐싱됨)
+        /// </summary>
+        public List<TowerData> GetBuildableBuildings()
+        {
+            if (_buildableCacheDirty || _buildableBuildingsCache == null)
+            {
+                _buildableBuildingsCache = new List<TowerData>();
+                foreach (var building in availableBuildings)
+                {
+                    if (building != null && building.level == 1)
+                    {
+                        _buildableBuildingsCache.Add(building);
+                    }
+                }
+                _buildableCacheDirty = false;
+            }
+            return _buildableBuildingsCache;
+        }
+
         public Vector3Int WorldToGrid(Vector3 worldPosition)
         {
             return new Vector3Int(