feat(webhooks): add foundation layer — migration, domain events, EventBus

k-tv-backend/api/src/events.rs

@@ -0,0 +1,12 @@
+//! Event bus type alias.
+//!
+//! The broadcast sender is kept in `AppState` and cloned into each route handler.
+//! Receivers are created with `event_tx.subscribe()`.
+
+use tokio::sync::broadcast;
+use domain::DomainEvent;
+
+/// A sender half of the domain-event broadcast channel.
+///
+/// Clone to share across tasks. Use `event_tx.subscribe()` to create receivers.
+pub type EventBus = broadcast::Sender<DomainEvent>;