Enable or disable Agentic Runtime Authority rule enforcement for this item.
When false, user-defined input/output rules are stored but not enforced;
the base security validation still runs.
AraEnabled is tri-state (nil/true/false), not a plain bool: it self-encodes
its wire value (see akl.OptionalBool) so an explicit false survives the
curl-proxy relay instead of being dropped like a default-false bool flag.