fix: Ensure CMake compiles for correct target architecture on macOS

- Add CMAKE_OSX_ARCHITECTURES flag to explicitly set target architecture
- Detect TARGET from Cargo environment and pass to CMake
- Use 'arch -x86_64' for CMake execution when cross-compiling on arm64 runner
- Fixes linker warnings about mismatched architectures (arm64 vs x86_64)

Author: eltorio