docs: 修正 API 文档准确性 (第三轮检查)

修复问题:
- containers: HashMap include 路径修复
- core: RefCounted 析构函数访问级别, Event::begin/end 返回值说明
- memory: LinearAllocator::GetMarker 返回偏移量非指针
- resources: LoadAsync 示例使用不存在的模板方法
- rhi: OpenGL 链接错误, ShaderType 枚举缺失8个类型, 链接修复
- threading: SpinLock STL 兼容方法说明, Mutex const 方法说明

docs/api/resources/resources.md

@@ -67,9 +67,12 @@ ResourceHandle<Mesh> mesh = ResourceManager::Get().Load<Mesh>("models/player.fbx
 ResourceHandle<Material> mat = ResourceManager::Get().Load<Material>("materials/player.mat");
 
 // 异步加载
-ResourceManager::Get().LoadAsync<Texture>("textures/terrain.png", 
-    [](ResourceHandle<Texture> tex) {
-        // 加载完成回调
+ResourceManager::Get().LoadAsync("textures/terrain.png", ResourceType::Texture,
+    [](LoadResult result) {
+        if (result.success) {
+            ResourceHandle<Texture> tex(result.resource);
+            // 加载完成回调
+        }
     });
 
 // 释放资源