Fix static graphics action builds

External/NativeStatic/README.md

@@ -0,0 +1,16 @@
+# Native Static Outputs
+
+GitHub Actions writes platform static libraries here before packing the NuGet package.
+
+Expected generated layout:
+
+```text
+External/NativeStatic/win-x64/native inputs
+External/NativeStatic/win-arm64/native inputs
+External/NativeStatic/linux-x64/native inputs
+External/NativeStatic/linux-arm64/native inputs
+External/NativeStatic/osx-x64/native inputs
+External/NativeStatic/osx-arm64/native inputs
+```
+
+The repository keeps build patches here, but platform `.a` and `.lib` outputs are generated by the workflow and are not source files.