feat(scene): 添加场景加载器接口定义

- 定义了 ISceneLoader<T> 接口用于管理场景加载、替换和卸载操作
- 提供 Current 属性获取当前加载的场景对象
- 添加 Replace 方法用于替换当前场景为指定键对应的场景
- 添加 Unload 方法用于卸载当前加载的场景
- 包含完整的 XML 文档注释说明接口功能和方法用途
- 遵循 Apache 2.0 许可证协议并添加版权信息

GFramework.Core.Abstractions/scene/ISceneLoader.cs

@@ -0,0 +1,37 @@
+// Copyright (c) 2026 GeWuYou
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//     http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace GFramework.Core.Abstractions.scene;
+
+/// <summary>
+/// 定义场景加载器的接口，用于管理场景的加载、替换和卸载操作。
+/// </summary>
+public interface ISceneLoader<out T>
+{
+    /// <summary>
+    /// 获取当前加载的场景对象。
+    /// </summary>
+    /// <returns>当前场景对象，如果未加载任何场景则返回 null。</returns>
+    T? Current { get; }
+
+    /// <summary>
+    /// 替换当前场景为指定键对应的场景。
+    /// </summary>
+    /// <param name="key">场景的唯一标识符或键值。</param>
+    void Replace(string key);
+
+    /// <summary>
+    /// 卸载当前加载的场景。
+    /// </summary>
+    void Unload();
+}