refactor: code smell fixes — tests, events, naming

- Tests for ExecutePipelineHandler (happy path, fallback, disabled skip, failure retry, not found)
- Tests for ProcessNextJobHandler (empty queue, process, drain multiple)
- DerivativeGenerated domain event + event-payload mapping + event_store aggregate
- Renamed event-payload → adapters-event-payload, event-transport → adapters-event-transport

crates/worker/src/main.rs

@@ -45,10 +45,11 @@ async fn main() -> anyhow::Result<()> {
 
     // Publisher transport consumes a client clone; the consumer gets another.
     let pub_transport = adapters_nats::NatsTransport::new(nats_client.clone());
-    let nats_publisher: Arc<dyn domain::ports::EventPublisher> =
-        Arc::new(event_transport::EventPublisherAdapter::new(pub_transport));
+    let nats_publisher: Arc<dyn domain::ports::EventPublisher> = Arc::new(
+        adapters_event_transport::EventPublisherAdapter::new(pub_transport),
+    );
     let event_pub: Arc<dyn domain::ports::EventPublisher> = Arc::new(
-        event_transport::CompositeEventPublisher::new(nats_publisher, event_store),
+        adapters_event_transport::CompositeEventPublisher::new(nats_publisher, event_store),
     );
 
     let extractor: Arc<dyn domain::ports::MetadataExtractorPort> =
@@ -97,7 +98,7 @@ async fn main() -> anyhow::Result<()> {
 
     // ── Event-driven loop via NATS ─────────────────────────────────────
     let consumer_source = adapters_nats::NatsMessageSource::new(nats_client);
-    let event_consumer = event_transport::EventConsumerAdapter::new(consumer_source);
+    let event_consumer = adapters_event_transport::EventConsumerAdapter::new(consumer_source);
 
     info!("event loop: listening for NATS events");
     let mut stream = event_consumer.consume();