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/read-write-lock/writelock.md

@@ -0,0 +1,41 @@
+# ReadWriteLock::WriteLock
+
+```cpp
+void WriteLock()
+```
+
+获取写锁（独占）。如果有读者持有锁或有其他写者正在等待，当前线程将阻塞，直到获得独占访问权。
+
+**参数：** 无
+
+**返回：** 无
+
+**线程安全：** ✅
+
+**复杂度：** 平均 O(1)，写者饥饿时可能 O(n)
+
+**注意：**
+- 写锁为独占访问，持有期间不允许任何读锁或写锁。
+- 写锁具有优先权，会阻塞后续到达的读者。
+- 同一线程不可重复 WriteLock。
+
+**示例：**
+
+```cpp
+#include "XCEngine/Threading/ReadWriteLock.h"
+#include <vector>
+
+XCEngine::Threading::ReadWriteLock rwLock;
+std::vector<int> buffer;
+
+void Append(int value) {
+    rwLock.WriteLock();
+    buffer.push_back(value);
+    rwLock.WriteUnlock();
+}
+```
+
+## 相关文档
+
+- [`ReadWriteLock`](readwritelock.md) - 返回类总览
+- [`WriteUnlock`](writeunlock.md) - 释放写锁