feat(event): add invoice.issued and invoice.paid event contracts

event/event.go

@@ -61,6 +61,13 @@ const (
 	// Payload is an order.Created (platform/order). See docs/inventory-shape.md
 	// and docs/fulfillment-stance.md.
 	OrderCreated Type = "order.created"
+	// InvoiceIssued is emitted when an order is invoiced (pay-later placement or
+	// manual invoice issuance). Payload is an order.InvoiceIssued (platform/order).
+	InvoiceIssued Type = "invoice.issued"
+	// InvoicePaid is emitted when an invoiced order payment status crosses to paid.
+	// Payload is an order.InvoicePaid (platform/order).
+	InvoicePaid Type = "invoice.paid"
+
 
 	// Analytics (tracking). Replaces the integer enum 0–6 that finder and
 	// slask-tracking use on the `tracking` topic today. Producer: slask-finder