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_BroadcastAlert.cs

@@ -0,0 +1,39 @@
+#if GRAPH_DESIGNER
+using Opsive.BehaviorDesigner.Runtime.Tasks;
+using Opsive.BehaviorDesigner.Runtime.Tasks.Actions;
+using UnityEngine;
+
+namespace BaseGames.Enemies.AI
+{
+    /// <summary>
+    /// BD Action：向半径内其他敌人广播警戒（Group Alert）。
+    ///
+    /// 返回 Success：广播完成（不保证命中任何敌人）。
+    ///
+    /// 典型用法：在 BD_SetAiPhase(Chase) 之后立即调用此节点，
+    /// 使发现玩家的敌人将警报传播给周围同伴，实现群体索敌效果。
+    ///
+    /// 半径优先使用 m_OverrideRadius；若为 0 则读取 EnemyStatsSO.AlertBroadcastRadius。
+    /// </summary>
+    [TaskName("Broadcast Alert")]
+    [TaskCategory("BaseGames/Enemy/Perception")]
+    [TaskDescription("向附近的友方广播警报，使其进入 Alert 状态")]
+    public class BD_BroadcastAlert : Action
+    {
+        [Tooltip("广播半径（m）；0 = 使用 EnemyStatsSO.AlertBroadcastRadius")]
+        [SerializeField, Min(0f)] private float m_OverrideRadius = 0f;
+
+        private EnemyBase _enemy;
+
+        public override void OnAwake() => _enemy = GetComponent<EnemyBase>();
+
+        public override TaskStatus OnUpdate()
+        {
+            if (_enemy == null) return TaskStatus.Failure;
+            float r = m_OverrideRadius > 0f ? m_OverrideRadius : (_enemy.StatsSO?.AlertBroadcastRadius ?? 0f);
+            _enemy.AlertNearby(r);
+            return TaskStatus.Success;
+        }
+    }
+}
+#endif