Make operator alerts explicit on shared ownership transitions

When a queue transition primitive is reused for both actionable escalation and silent lifecycle cleanup, ownership change alone is not enough to trigger an operator alert. Keep alert intent explicit and default-false at the call site, create the alert transactionally with the canonical transition event, and deduplicate by that event. This prevents completion, cancellation, or obsolete-obligation cleanup from flooding humans while preserving one alert per genuine handoff. The rule is unnecessary when every transition to the target state always requires attention.

Applies when: A shared state-transition helper serves both urgent handoffs and routine cleanup. Keywords: operator alert human handoff ownership transition cleanup idempotency transaction