TMS: API with DISABLE_EMBEDDED_WORKERS=true delivers no domain events to any handler #327

Problem

PgBossEventBus.publish records each event in DomainEventLog, then sends it only to queues for handlers registered in the same process (fanOut walks its local registry). When the API runs with DISABLE_EMBEDDED_WORKERS=true, the documented setup for a separate worker container (docs/SELF_HOSTING.md), index.ts never calls registerEventHandlers. So the API's registry is empty, and every event its commands publish is recorded and delivered nowhere.

In that setup, nothing done through the API reaches:

• projections: shipment/order read models, list views, timeline
• audit, notifications, email, customer webhooks, triage
• EDI auto-send and billing triggers

The standalone worker can't pick them up either, because nothing is ever put on the evt.* queues.

The default docker-compose.yml doesn't set the flag, so the API still runs its own handlers there and isn't affected. Any deployment that follows the separate-worker docs is affected.

Suggested fix

Make fan-out independent of who consumes. The API needs to know every handler's queue name and patterns without consuming from them. For example, registerEventHandlers could register routing for each handler on every process, with eventBus.start() (which subscribes to queues) only called where handlers should run. An alternative is a static routing table built from the handler list.

Acceptance criteria

• With DISABLE_EMBEDDED_WORKERS=true on the API and a WORKER_MODE=all worker, creating a shipment through the API updates ShipmentReadModel and the timeline.
• No handler runs twice when the API has embedded workers enabled.
• A test covers fan-out from a process that registers routing but doesn't consume.

Related: found while fixing #287.