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-system-config/thread-stack-size.md

@@ -0,0 +1,28 @@
+# TaskSystemConfig::threadStackSize
+
+```cpp
+uint32_t threadStackSize = 0
+```
+
+工作线程的栈大小（字节）。值为 0 时使用系统默认值。
+
+**类型：** `uint32_t`
+
+**默认值：** `0`（使用系统默认）
+
+**当前状态：** 此配置项当前未实际使用，工作线程始终使用系统默认栈大小。
+
+**示例：**
+
+```cpp
+TaskSystemConfig config;
+config.workerThreadCount = 4;
+config.threadStackSize = 1024 * 1024; // 预留配置项（当前未实现）
+
+TaskSystemConfig defaultConfig;
+defaultConfig.threadStackSize = 0; // 使用系统默认
+```
+
+## 相关文档
+
+- [TaskSystemConfig 总览](tasksystemconfig.md) - 返回类总览