Function sidecar_path 

pub fn sidecar_path(db_path: &Path, filename: &str) -> PathBuf

Derives a sidecar file path next to the database (e.g. the enrich/ingest queue), so worklist files follow --db instead of the process CWD. Falls back to the bare filename (CWD) when db_path has no parent — preserving the legacy default-DB layout.