refactor(RHI): 将窗口职责从RHI移到Platform层

- RHIDeviceDesc 删除 windowHandle/width/height/appName
- SwapChainDesc 添加 windowHandle 字段
- RHISwapChain 删除 PollEvents/ShouldClose/SetFullscreen 等窗口相关接口
- OpenGLDevice 删除 CreateRenderWindow，改用 InitializeWithExistingWindow
- 更新所有集成测试使用新API
- 273个单元测试 + 8个集成测试全部通过

tests/RHI/OpenGL/unit/test_device.cpp

@@ -3,24 +3,6 @@
 
 using namespace XCEngine::RHI;
 
-TEST_F(OpenGLTestFixture, Device_CreateRenderWindow_ValidParams) {
-    OpenGLDevice device;
-
-    bool result = device.CreateRenderWindow(800, 600, "Test Window", false);
-
-    ASSERT_TRUE(result);
-    ASSERT_NE(device.GetWindow(), nullptr);
-}
-
-TEST_F(OpenGLTestFixture, Device_CreateRenderWindow_DebugMode) {
-    OpenGLDevice device;
-
-    bool result = device.CreateRenderWindow(640, 480, "Debug Window", true);
-
-    ASSERT_TRUE(result);
-    ASSERT_NE(device.GetWindow(), nullptr);
-}
-
 TEST_F(OpenGLTestFixture, Device_InitializeWithExistingWindow) {
     OpenGLDevice device;
     HWND existingWindow = GetWindow();
@@ -28,12 +10,11 @@ TEST_F(OpenGLTestFixture, Device_InitializeWithExistingWindow) {
     bool result = device.InitializeWithExistingWindow(existingWindow);
 
     ASSERT_TRUE(result);
-    ASSERT_EQ(device.GetWindow(), existingWindow);
 }
 
 TEST_F(OpenGLTestFixture, Device_GetDeviceInfo_ReturnsValid) {
     OpenGLDevice device;
-    device.CreateRenderWindow(800, 600, "Test", false);
+    device.InitializeWithExistingWindow(GetWindow());
 
     const auto& info = device.GetDeviceInfo();
 
@@ -45,19 +26,10 @@ TEST_F(OpenGLTestFixture, Device_GetDeviceInfo_ReturnsValid) {
 
 TEST_F(OpenGLTestFixture, Device_SwapBuffers_NoErrors) {
     OpenGLDevice device;
-    device.CreateRenderWindow(800, 600, "Test", false);
+    device.InitializeWithExistingWindow(GetWindow());
 
     device.SwapBuffers();
 
     GLenum error = glGetError();
     EXPECT_EQ(error, GL_NO_ERROR);
-}
-
-TEST_F(OpenGLTestFixture, Device_PollEvents_ReturnsTrue) {
-    OpenGLDevice device;
-    device.CreateRenderWindow(800, 600, "Test", false);
-
-    bool result = device.PollEvents();
-
-    EXPECT_TRUE(result);
-}
+}