An agent's change cannot be told apart from an admin's or reconstructed later

The audit writes one op.call line per call: operation, transport, outcome, principal and user agent, but never inputs. Stored settings, worlds and questions carry version and updatedAt but no author. Once an agent has saved, nothing records what it changed or that it was an agent. Yet settingsChange already computes a list of what changed (section, key, from and to) for every settings save.

Impact: Recording who changed what turns agent edits into reviewable history, the precondition for letting agents write outside development.

Recommendation (medium effort): Store the actor (transport and principal) on each saved record, and log the settingsChange list with each settings write; add an equivalent field diff for worlds and questions.