Function create_env_file 

pub fn create_env_file(
    hip_visible_devices: &str,
    rocm_path: &str,
    rocm_version: &str,
    rocm_channel: &str,
    gpu_arch: &str,
    hsa_override_gfx_version: &str,
    python_bin: &str,
) -> EnvFileResult

Create the ~/.mlstack_env file with all required variables.

Generates a shell-sourceable file with GPU settings, ROCm paths, performance optimizations, and PyTorch/MPI settings.

Validation

• VAL-VBA-016: Environment file creation produces shell-sourceable ~/.mlstack_env