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.

utils/trackEvent.test.ts

@@ -0,0 +1,51 @@
+import { afterEach, beforeEach, expect, test } from "bun:test";
+
+const sent: Array<[string, unknown]> = [];
+beforeEach(() => {
+	sent.length = 0;
+	(globalThis as any).window = {};
+});
+afterEach(async () => {
+	const { __resetTrackQueue } = await import("./trackEvent");
+	__resetTrackQueue();
+	delete (globalThis as any).window;
+});
+const umami = { track: (e: string, d: unknown) => sent.push([e, d]) };
+const wait = (ms: number) => new Promise((r) => setTimeout(r, ms));
+
+test("sends immediately when umami is loaded", async () => {
+	const { trackEvent } = await import("./trackEvent");
+	(globalThis as any).window.umami = umami;
+	trackEvent("a", { x: 1 });
+	expect(sent).toEqual([["a", { x: 1 }]]);
+});
+
+test("queues until umami appears, then flushes in order and calls onSent", async () => {
+	const { trackEvent } = await import("./trackEvent");
+	let confirmed = false;
+	trackEvent("first");
+	trackEvent("purchase-completed", { revenue: 12.5, currency: "EUR" }, () => (confirmed = true));
+	expect(sent).toEqual([]);
+	await wait(300);
+	(globalThis as any).window.umami = umami;
+	await wait(400);
+	expect(sent.map((s) => s[0])).toEqual(["first", "purchase-completed"]);
+	expect(confirmed).toBe(true);
+});
+
+test("never throws and drops events when umami never loads", async () => {
+	const { trackEvent } = await import("./trackEvent");
+	let confirmed = false;
+	trackEvent("lost", undefined, () => (confirmed = true));
+	await wait(10_500);
+	(globalThis as any).window.umami = umami;
+	await wait(400);
+	expect(sent).toEqual([]);
+	expect(confirmed).toBe(false);
+}, 15_000);
+
+test("is a no-op on the server", async () => {
+	delete (globalThis as any).window;
+	const { trackEvent } = await import("./trackEvent");
+	expect(() => trackEvent("ssr")).not.toThrow();
+});