- pii_catalog: persistent per-column masking policy (default masked); GET/POST
/api/pii/policy and POST /api/pii/lookup which redacts masked values server-side.
- get_pii masked flag now reflects the policy; dataflow exposes the dataset key.
- Data Flow PII inspector: per-column lock/unlock toggles + mask-all/unmask-all,
so operators control exactly which data the assistant may reveal.