Module write_provenance 

Engine surface for write provenance.

• Record a tamper-evident provenance entry on the REMEMBER / SHARE write path (chained onto the store’s head).
• Query it: by memory id, by principal, by session/trace id.
• Verify the whole chain is intact (tamper-evidence).
• FORGET BY PROVENANCE: revoke everything a principal or session wrote in one call. This is the point — after a poisoning incident, targeted cleanup by the responsible principal/session instead of wiping the store.