refactor: improve test infrastructure and fix OpenGL GLAD initialization

- Rename D3D12Enum.h to D3D12Enums.h for naming consistency
- Fix OpenGL unit test GLAD initialization by using gladLoadGL()
  instead of gladLoadGLLoader(wglGetProcAddress) for fallback support
- Migrate remaining tests to use gtest_discover_tests for granular
  test discovery (math, core, containers, memory, threading, debug,
  components, scene, resources, input, opengl)
- Remove obsolete TEST_RESOURCES_DIR and copy_directory commands
  from OpenGL unit test CMakeLists (minimal/Res doesn't exist)
- Update TEST_SPEC.md with performance metrics and per-module
  build/test commands for faster development workflow
- Update CMake path references to use lowercase paths

docs/api/threading/task-group/destructor.md

@@ -0,0 +1,40 @@
+# TaskGroup::~TaskGroup
+
+```cpp
+~TaskGroup();
+```
+
+析构函数。销毁任务组。
+
+**参数：** 无
+
+**返回：** 无
+
+**线程安全：** ⚠️
+
+**复杂度：** O(n)，n 为任务组中的任务数
+
+**注意：**
+- 析构前会等待所有任务完成。
+- 如果有任务正在执行，会等待其完成。
+- 未执行的任务将被取消。
+
+**示例：**
+
+```cpp
+#include "XCEngine/Threading/TaskGroup.h"
+
+{
+    XCEngine::Threading::TaskGroup group;
+    group.AddTask([]() {
+        // 执行任务...
+    });
+    group.Wait();
+} // group 在这里销毁
+```
+
+## 相关文档
+
+- [`TaskGroup`](task-group.md) - 返回类总览
+- [`Cancel`](cancel.md) - 取消任务
+- [`Wait`](wait.md) - 等待任务完成