chore: import upstream snapshot with attribution

examples/gpu-surface/README.md

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+# Native SDK gpu-surface example
+
+This example shows a real GPU-backed child surface in the native view tree:
+
+- A native toolbar and statusbar.
+- A Metal-backed `gpu_surface` pane with explicit pixel format, presentation, alpha, color-space, and vsync settings.
+- A WebView sibling pane in the same split layout.
+- Native controls that dispatch commands back to Zig.
+
+Run with the macOS system backend. The GPU surface example defaults to `ReleaseFast`; pass `-Doptimize=Debug` only when debugging renderer internals.
+
+```sh
+native dev
+```
+
+Run the headless declaration test:
+
+```sh
+native test -Dplatform=null
+```