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/inflight_test.go

@@ -84,9 +84,9 @@ func TestSweepLeavesAQueuedDeliveryAlone(t *testing.T) {
 	)
 	rAgePending(t, s.WebhookDB, d.ID)
 
-	// Queued exactly as the receiver queues it, and never dequeued:
+	// Queued exactly as StoreEvent queues it, and never dequeued:
 	// no workers are running in this engine.
-	s.Engine.Notify([]delivery.Task{{
+	s.Engine.ExportNotify([]delivery.Task{{
 		DeliveryID: d.ID,
 		EventID:    event.ID,
 		WebhookID:  s.WebhookID,
@@ -109,7 +109,7 @@ func TestSweepLeavesAQueuedDeliveryAlone(t *testing.T) {
 
 // TestRecoveryAndSweepDoNotDoubleDispatch drives the recovery routine's
 // run at start and a tick of the sweep at once against one aged pending
-// row. The engine runs them one after the other, but Notify can race
+// row. The engine runs them one after the other, but notify can race
 // either, and ownership is what keeps any two claimants from both
 // sending. Before ownership the two runs both dispatched the row.
 func TestRecoveryAndSweepDoNotDoubleDispatch(t *testing.T) {
@@ -224,7 +224,7 @@ func TestOwnershipIsReleasedAfterDelivery(t *testing.T) {
 
 	body := `{"released":true}`
 
-	s.Engine.Notify([]delivery.Task{{
+	s.Engine.ExportNotify([]delivery.Task{{
 		DeliveryID:   d.ID,
 		EventID:      event.ID,
 		WebhookID:    s.WebhookID,
@@ -248,10 +248,10 @@ func TestOwnershipIsReleasedAfterDelivery(t *testing.T) {
 }
 
 // TestNotifyAfterRecoveryDoesNotSendAgain is the startup race of
-// https://git.eeqj.de/sneak/webhooker/issues/299. The receiver has
+// https://git.eeqj.de/sneak/webhooker/issues/299. StoreEvent has
 // written a delivery, the recovery routine's run at start finds it
-// pending, sends it and releases it, and only then does the receiver's
-// Notify for it arrive. Nothing owns the delivery by then, so Notify
+// pending, sends it and releases it, and only then does StoreEvent's
+// notify for it arrive. Nothing owns the delivery by then, so notify
 // takes it.
 func TestNotifyAfterRecoveryDoesNotSendAgain(t *testing.T) {
 	t.Parallel()
@@ -289,7 +289,7 @@ func TestNotifyAfterRecoveryDoesNotSendAgain(t *testing.T) {
 
 	body := event.Body
 
-	s.Engine.Notify([]delivery.Task{{
+	s.Engine.ExportNotify([]delivery.Task{{
 		DeliveryID:   d.ID,
 		EventID:      event.ID,
 		WebhookID:    s.WebhookID,
@@ -300,7 +300,7 @@ func TestNotifyAfterRecoveryDoesNotSendAgain(t *testing.T) {
 		EntrypointID: event.EntrypointID,
 	}})
 
-	// Notify took the delivery, and a worker releases it once it has
+	// notify took the delivery, and a worker releases it once it has
 	// run the task.
 	require.Eventually(
 		t,