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/UIEditorViewportShell.cpp

@@ -65,14 +65,13 @@ UIEditorViewportShellRequest ResolveUIEditorViewportShellRequest(
 
 UIEditorViewportShellFrame UpdateUIEditorViewportShell(
     UIEditorViewportShellState& state,
-    const ::XCEngine::UI::UIRect& bounds,
+    const UIEditorViewportShellRequest& request,
     const UIEditorViewportShellModel& model,
     const std::vector<::XCEngine::UI::UIInputEvent>& inputEvents,
-    const Widgets::UIEditorViewportSlotMetrics& metrics,
     const UIEditorViewportInputBridgeRequest& inputRequest) {
     UIEditorViewportShellFrame frame = {};
-    frame.slotLayout = BuildViewportShellLayout(bounds, model.spec, model.frame, metrics);
-    frame.requestedViewportSize = frame.slotLayout.requestedSurfaceSize;
+    frame.slotLayout = request.slotLayout;
+    frame.requestedViewportSize = request.requestedViewportSize;
     frame.inputFrame = UpdateUIEditorViewportInputBridge(
         state.inputBridgeState,
         frame.slotLayout.bounds,
@@ -88,4 +87,21 @@ UIEditorViewportShellFrame UpdateUIEditorViewportShell(
     return frame;
 }
 
+UIEditorViewportShellFrame UpdateUIEditorViewportShell(
+    UIEditorViewportShellState& state,
+    const ::XCEngine::UI::UIRect& bounds,
+    const UIEditorViewportShellModel& model,
+    const std::vector<::XCEngine::UI::UIInputEvent>& inputEvents,
+    const Widgets::UIEditorViewportSlotMetrics& metrics,
+    const UIEditorViewportInputBridgeRequest& inputRequest) {
+    const UIEditorViewportShellRequest request =
+        ResolveUIEditorViewportShellRequest(bounds, model.spec, metrics);
+    return UpdateUIEditorViewportShell(
+        state,
+        request,
+        model,
+        inputEvents,
+        inputRequest);
+}
+
 } // namespace XCEngine::UI::Editor