Constant GIX_VERSION 

pub const GIX_VERSION: &str = "0.86.0";

Pinned gix version embedded in every provenance manifest. Surfaced both in JSON sidecars and the pre-flight banner header. Kept in sync with the gix dep in workspace Cargo.toml via tests/dep_versions_drift_test.rs, which fails CI if these constants and Cargo.lock drift apart.