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/mutex/try-lock-const.md

@@ -0,0 +1,41 @@
+# Mutex::try_lock
+
+```cpp
+bool try_lock() const;
+```
+
+尝试获取互斥锁（非阻塞，const 版本）。如果锁可用则立即获取并返回 `true`，否则立即返回 `false` 而不阻塞。
+
+该方法是 `std::lockable` 接口的实现。
+
+**参数：** 无
+
+**返回：** `bool` - 获取成功返回 `true`，锁不可用返回 `false`
+
+**线程安全：** ✅
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+#include "XCEngine/Threading/Mutex.h"
+#include <iostream>
+
+XCEngine::XCEngine::Threading::Mutex mtx;
+volatile bool updated = false;
+
+void TryUpdate() {
+    if (mtx.try_lock()) {
+        updated = true;
+        mtx.unlock();
+        std::cout << "Update succeeded" << std::endl;
+    } else {
+        std::cout << "Update skipped (lock held)" << std::endl;
+    }
+}
+```
+
+## 相关文档
+
+- [Mutex 总览](mutex.md) - 返回类总览