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/World/RoomState.cs

@@ -0,0 +1,29 @@
+namespace BaseGames.World
+{
+    /// <summary>
+    /// 房间在流式加载系统中的生命周期状态。
+    /// </summary>
+    public enum RoomState
+    {
+        /// <summary>未加载，资产不在内存中。</summary>
+        Unloaded,
+
+        /// <summary>正在后台异步加载中。</summary>
+        Loading,
+
+        /// <summary>已加载并初始化，处于休眠状态：渲染器、AI、物理均已关闭，不消耗 CPU。</summary>
+        Dormant,
+
+        /// <summary>正在激活中（分帧启用 AI）。</summary>
+        Activating,
+
+        /// <summary>完全激活，玩家当前所在的房间。</summary>
+        Active,
+
+        /// <summary>玩家已离开，等待冷却计时后转为 Dormant 或 Unloaded。</summary>
+        Cooling,
+
+        /// <summary>正在后台异步卸载中。</summary>
+        Unloading,
+    }
+}