Carry backing resource in UI texture handles

engine/include/XCEngine/UI/Types.h

@@ -52,6 +52,7 @@ struct UITextureHandle {
     std::uint32_t width = 0;
     std::uint32_t height = 0;
     UITextureHandleKind kind = UITextureHandleKind::DescriptorHandle;
+    std::uintptr_t resourceHandle = 0;
 
     constexpr bool IsValid() const {
         return nativeHandle != 0 && width > 0 && height > 0;

new_editor/app/Viewport/ProductViewportRenderTargets.h

@@ -229,6 +229,8 @@ inline bool CreateViewportTextureDescriptor(
     targets.textureHandle.width = targets.width;
     targets.textureHandle.height = targets.height;
     targets.textureHandle.kind = ::XCEngine::UI::UITextureHandleKind::ShaderResourceView;
+    targets.textureHandle.resourceHandle =
+        reinterpret_cast<std::uintptr_t>(targets.colorTexture);
     return true;
 }