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/app/Rendering/D3D12/D3D12UiTextSystem.h

@@ -0,0 +1,85 @@
+#pragma once
+
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
+
+#include <XCEditor/Foundation/UIEditorTextMeasurement.h>
+
+#include <dwrite.h>
+#include <windows.h>
+#include <wrl/client.h>
+
+#include <cstdint>
+#include <string>
+#include <string_view>
+#include <unordered_map>
+#include <vector>
+
+namespace XCEngine::UI::Editor::Host {
+
+class D3D12UiTextSystem final : public ::XCEngine::UI::Editor::UIEditorTextMeasurer {
+public:
+    struct ShapedGlyph {
+        Microsoft::WRL::ComPtr<IDWriteFontFace> fontFace = {};
+        std::uint16_t glyphIndex = 0u;
+        float fontEmSize = 0.0f;
+        float originX = 0.0f;
+        float originY = 0.0f;
+        DWRITE_MEASURING_MODE measuringMode = DWRITE_MEASURING_MODE_NATURAL;
+        bool isSideways = false;
+    };
+
+    struct ShapedTextRun {
+        std::vector<ShapedGlyph> glyphs = {};
+        float width = 0.0f;
+        float height = 0.0f;
+    };
+
+    struct RasterizedGlyph {
+        std::vector<std::uint8_t> rgbaPixels = {};
+        UINT width = 0u;
+        UINT height = 0u;
+        LONG boundsLeft = 0;
+        LONG boundsTop = 0;
+        LONG boundsRight = 0;
+        LONG boundsBottom = 0;
+    };
+
+    bool Initialize();
+    void Shutdown();
+
+    void SetDpiScale(float dpiScale);
+    float GetDpiScale() const;
+    const std::string& GetLastError() const;
+
+    float MeasureTextWidth(
+        const ::XCEngine::UI::Editor::UIEditorTextMeasureRequest& request) const override;
+    bool ShapeTextRun(
+        std::string_view text,
+        float fontSize,
+        ShapedTextRun& outRun,
+        std::string& outError) const;
+    bool RasterizeGlyph(
+        const ShapedGlyph& glyph,
+        RasterizedGlyph& outGlyph,
+        std::string& outError) const;
+    bool RasterizeTextMask(
+        std::string_view text,
+        float fontSize,
+        std::vector<std::uint8_t>& outRgbaPixels,
+        UINT& outWidth,
+        UINT& outHeight,
+        std::string& outError);
+
+private:
+    IDWriteTextFormat* GetTextFormat(float fontSize) const;
+    static std::wstring Utf8ToWide(std::string_view text);
+
+    Microsoft::WRL::ComPtr<IDWriteFactory> m_dwriteFactory = {};
+    mutable std::unordered_map<int, Microsoft::WRL::ComPtr<IDWriteTextFormat>> m_textFormats = {};
+    float m_dpiScale = 1.0f;
+    std::string m_lastError = {};
+};
+
+} // namespace XCEngine::UI::Editor::Host