Analytics: queued events, once-per-order revenue, heatmap on product pages

trackEvent queues events until the deferred Umami script exists (they
were dropped when fired in onMounted) and drops them silently after 10 s.
The result page sends purchase-completed with revenue/currency once per
order (localStorage guard, set only after sending). The plugin honours
Do Not Track and loads recorder.js only on /details/* for Umami heatmaps.
bun test utils/trackEvent.test.ts: 4 pass. Netcup #115.

pages/checkout/result/[uuid].vue

@@ -151,6 +151,23 @@ onMounted(async () => {
 					orderTotal: order.value.total,
 					itemCount: order.value.cart?.length ?? 0
 				});
+
+				// Revenue for Umami's revenue report: exactly once per order, even if the
+				// customer reloads this page or opens it again from the confirmation mail.
+				const purchaseKey = `mp-purchase-tracked-${order.value.uuid}`;
+				if (!localStorage.getItem(purchaseKey)) {
+					const products = (order.value.cart ?? []).map((item) => item.product?.slug).filter(Boolean);
+					trackEvent(
+						"purchase-completed",
+						{
+							revenue: order.value.total,
+							currency: "EUR",
+							itemCount: (order.value.cart ?? []).reduce((sum, item) => sum + (item.count ?? 1), 0),
+							products: products.join(",").slice(0, 400)
+						},
+						() => localStorage.setItem(purchaseKey, new Date().toISOString())
+					);
+				}
 			}
 
 			if (order.value?.invoice?.url) {