checkpoint(new_editor): native d3d12 ui path

Key node 1: move main-window UI presentation onto the D3D12 render loop with native UI renderer, text system, and texture host.

Key node 2: wire frame timing/FPS display, window runtime, swapchain presentation, and native screenshot capture around the new path.

Key node 3: carry editor shell/workspace/viewport/panel interaction updates needed by the new renderer and detached window flow.

Key node 4: pump async resource loads and scene bridge follow-up needed for scene content visibility in new_editor.

new_editor/src/Viewport/UIEditorViewportSlot.cpp

@@ -372,7 +372,8 @@ void AppendUIEditorViewportSlotForeground(
     const std::vector<UIEditorStatusBarSegment>& statusSegments,
     const UIEditorViewportSlotState& state,
     const UIEditorViewportSlotPalette& palette,
-    const UIEditorViewportSlotMetrics& metrics) {
+    const UIEditorViewportSlotMetrics& metrics,
+    const UIEditorViewportSlotForegroundAppendOptions& options) {
     if (layout.hasTopBar) {
         if (!chrome.title.empty()) {
             drawList.AddText(
@@ -405,7 +406,9 @@ void AppendUIEditorViewportSlotForeground(
         }
     }
 
-    if (frame.hasTexture && frame.texture.IsValid()) {
+    if (options.includeSurfaceTexture &&
+        frame.hasTexture &&
+        frame.texture.IsValid()) {
         drawList.AddImage(layout.textureRect, frame.texture, palette.imageTint);
     }
 
@@ -419,6 +422,18 @@ void AppendUIEditorViewportSlotForeground(
     }
 }
 
+void AppendUIEditorViewportSlotSurfaceTexture(
+    UIDrawList& drawList,
+    const UIEditorViewportSlotLayout& layout,
+    const UIEditorViewportSlotFrame& frame,
+    const UIEditorViewportSlotPalette& palette) {
+    if (!frame.hasTexture || !frame.texture.IsValid()) {
+        return;
+    }
+
+    drawList.AddImage(layout.textureRect, frame.texture, palette.imageTint);
+}
+
 void AppendUIEditorViewportSlot(
     UIDrawList& drawList,
     const UIRect& bounds,
@@ -454,7 +469,8 @@ void AppendUIEditorViewportSlot(
         statusSegments,
         state,
         palette,
-        metrics);
+        metrics,
+        {});
 }
 
 } // namespace XCEngine::UI::Editor::Widgets