v0.3.16

Fixed

• Derived Metric: event-leak between rules (script's event reference is now a per-evaluation snapshot, not the cached one)
• Derived Metric: reserved-name guard — metric names that collide with reserved contextdata keys (airlock, airlock_type, airlock.status, airlock.error, &&events, &&products) are now rejected at resolution time
• Derived Metric: per-entry error tolerance — one misbehaving metric no longer aborts the rest