Function run 

pub fn run(
    manifest_path: &Path,
    out: &Path,
    harness_path: Option<&str>,
    catalog_path: Option<&Path>,
    built_at: Option<&str>,
    builder: Option<&str>,
) -> Result<(), String>

Runs fz build.

catalog_path selects a release-stamped catalog (issue #142); None uses the built-in catalog whose seed pins carry the visible placeholder digest — fine for local development, refused by any attested build. built_at and builder are recorded verbatim in provenance; the CLI owns no clock and invents nothing.

Errors

A human-readable message if the manifest or catalog cannot be read, parsed, resolved, or written; or if an environment that claims sanctioned-build status fails the contract.