Native Static Outputs

GitHub Actions writes platform static libraries here before packing the NuGet package.

Expected generated layout:

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.