Workflow step that requests emission of a Blue event from the current invocation. Trigger Event constructs an event payload and returns it as a processor effect. It does not directly deliver to external parties or arbitrary channels; the Blue Contracts processor records, validates, charges, enqueues, bridges, routes, and exposes the emitted event according to its event/FIFO/outbox rules. Trigger Event is useful for notifying participants, asking another scope to act, producing domain events, or creating follow-up Operation Requests. The event payload must be a valid Blue node. Construction work, such as BEX execution, is charged by the compute/runtime layer; successful processor emission and routing are charged by Blue Contracts gas.