feat: Implement Room Streaming System

- Add RoomStreamingManager to manage room loading and unloading based on player proximity.
- Create StreamingBudgetConfigSO for memory and performance budgeting of the streaming system.
- Introduce TransitionDirector to handle seamless and atmospheric fade transitions between rooms.
- Develop WorldGraph to represent room connectivity and facilitate neighbor queries and distance calculations.
- Implement RoomNode and RoomEdge classes to structure room data and connections.

Assets/_Game/Scripts/Enemies/AI/BD_SetAiPhase.cs

@@ -0,0 +1,34 @@
+#if GRAPH_DESIGNER
+using UnityEngine;
+using Opsive.BehaviorDesigner.Runtime.Tasks;
+using Opsive.BehaviorDesigner.Runtime.Tasks.Actions;
+using BaseGames.Enemies;
+
+namespace BaseGames.Enemies.AI
+{
+    /// <summary>
+    /// BD Action：设置 AI 行为阶段（<see cref="AiPhase"/>）。
+    /// 单帧完成，返回 Success。常用于行为树中作为阶段过渡的标记节点，
+    /// 例如在 Selector 分支开头标记当前进入了哪个阶段。
+    /// </summary>
+    [TaskName("Set Ai Phase")]
+    [TaskCategory("BaseGames/Enemy/State")]
+    [TaskDescription("立即切换 AI 行为阶段（AiPhase），单帧返回 Success")]
+    public sealed class BD_SetAiPhase : Action
+    {
+        [Tooltip("目标 AI 行为阶段")]
+        [SerializeField] private AiPhase m_Phase = AiPhase.Idle;
+
+        private EnemyBase _enemy;
+
+        public override void OnAwake() => _enemy = gameObject.GetComponent<EnemyBase>();
+
+        public override TaskStatus OnUpdate()
+        {
+            if (_enemy == null) return TaskStatus.Failure;
+            _enemy.SetAiPhase(m_Phase);
+            return TaskStatus.Success;
+        }
+    }
+}
+#endif