Function save_project 

pub fn save_project(
    path: impl AsRef<Path>,
    project: &ProjectRecord,
    options: ProjectSaveOptions,
) -> Result<PathBuf, PersistenceError>

Save one validated native project as canonical JSON plus NPZ.

Only manifest.json and arrays.npz are created or replaced; unrelated files in an existing directory remain untouched.

Errors

Returns PersistenceError for invalid domain state, unsupported values, serialization, archive, filesystem, or overwrite failures.