Store events and create deliveries in the delivery engine (closes #544)

The receiver, resubmit and replay handlers now read and check the
request and make one call. Engine.StoreEvent stores an event with a
pending delivery for each active target and the totals in one
transaction, then queues them; Engine.CreateReplay does the same for
one replay delivery. The handlers take *delivery.Engine, so the
Notifier interface and its bridge are gone, and the engine's notify is
no longer exported. Archives and CircuitBreakers stay because the
handler tests fake them. The tests that read a queued task moved to
the engine's tests; the handler tests use an engine that is never
started.

Model: opus-5-5

internal/delivery/engine_lifecycle_test.go

@@ -29,7 +29,7 @@ const (
 	// OnStart before the caller may enqueue work. A worker pool
 	// wrongly rooted in the already-done hook context has nothing
 	// but ctx.Done() ready in its select, so it is deterministically
-	// gone by the end of this window. Without the wait, Notify would
+	// gone by the end of this window. Without the wait, notify would
 	// race the pool's very first select, in which a ready ctx.Done()
 	// and a ready deliveryCh are chosen between at random and a
 	// doomed pool still delivers.
@@ -182,7 +182,7 @@ func TestEngine_WorkersOutliveStartHookContext(t *testing.T) {
 	// routine's run at start cannot enqueue it.
 	deliveryID, task := seedLogTask(t, s)
 
-	s.Engine.Notify([]delivery.Task{task})
+	s.Engine.ExportNotify([]delivery.Task{task})
 
 	iWaitForDelivered(t, s.WebhookDB, deliveryID)
 }
@@ -202,7 +202,7 @@ func TestEngine_StopHookStopsWorkers(t *testing.T) {
 	// Let the pool prove it is running before stopping it, so a
 	// fast OnStop cannot pass by stopping something already dead.
 	firstID, firstTask := seedLogTask(t, s)
-	s.Engine.Notify([]delivery.Task{firstTask})
+	s.Engine.ExportNotify([]delivery.Task{firstTask})
 	iWaitForDelivered(t, s.WebhookDB, firstID)
 
 	var stopErr error
@@ -232,7 +232,7 @@ func TestEngine_StopHookStopsWorkers(t *testing.T) {
 	// With every worker gone, a freshly notified task must sit
 	// untouched in the queue rather than being delivered.
 	secondID, secondTask := seedLogTask(t, s)
-	s.Engine.Notify([]delivery.Task{secondTask})
+	s.Engine.ExportNotify([]delivery.Task{secondTask})
 
 	time.Sleep(200 * time.Millisecond)
 
@@ -383,7 +383,7 @@ func TestEngine_StopLeavesFireAndForgetAttemptPending(t *testing.T) {
 		t, s, 1, database.DeliveryStatusPending, 1,
 	)
 
-	s.Engine.Notify([]delivery.Task{task})
+	s.Engine.ExportNotify([]delivery.Task{task})
 	stopDuringAttempt(t, lc, arrived)
 
 	iAssertStatus(
@@ -448,7 +448,7 @@ func deliverToArchive(t *testing.T, s iSetup) string {
 	task.TargetID = tgt.ID
 	task.TargetType = database.TargetTypeDatabase
 
-	s.Engine.Notify([]delivery.Task{task})
+	s.Engine.ExportNotify([]delivery.Task{task})
 
 	iWaitForDelivered(t, s.WebhookDB, deliveryID)