Show each target's delivered and failed deliveries in the target list (closes #372)

Each row of the webhook page's target list now shows the target's
delivered and failed deliveries, in total and in the last 24 hours.
The totals are the target's running totals, so retention does not
reduce them; the 24-hour figures are counted over that window of the
deliveries' status index, in one query for all targets. Deliveries
still pending or retrying count in neither.

Model: opus-5-5

internal/server/alpine_browser_test.go

@@ -47,7 +47,8 @@ const (
 // TestAlpineRunsUnderTheSecurityPolicy loads the webhook page and the
 // event log in a headless browser, served by the real router and so
 // under the real Content-Security-Policy, and checks that the pages'
-// Alpine.js directives and the copy control work.
+// Alpine.js directives and the copy control work, and that a target's
+// row shows its delivery counts.
 func TestAlpineRunsUnderTheSecurityPolicy(t *testing.T) {
 	t.Parallel()
 
@@ -118,6 +119,9 @@ func TestAlpineRunsUnderTheSecurityPolicy(t *testing.T) {
 	}
 
 	checkRefusedTarget(ctx, t, page)
+	checkTargetDeliveries(ctx, t, page, target.Name,
+		"0 in total, 0 in the last 24 hours",
+		"1 in total, 1 in the last 24 hours")
 	checkCopy(ctx, t, page)
 	checkEntrypointEdit(ctx, t, page, page+"/events")
 	checkRecentEvents(ctx, t, page)
@@ -452,6 +456,28 @@ func checkRefusedTarget(ctx context.Context, t *testing.T, url string) {
 	assert.Empty(t, typed, "after Cancel, the next Add keeps the url entered")
 }
 
+// checkTargetDeliveries loads a webhook page and checks that the row of
+// the target named name shows delivered and failed beside its
+// "Delivered:" and "Failed:" labels.
+func checkTargetDeliveries(
+	ctx context.Context, t *testing.T, url, name, delivered, failed string,
+) {
+	t.Helper()
+
+	row := `//span[text()="` + name + `"]/ancestor::div[@class="p-4"][1]`
+	figure := func(label, value string) string {
+		return row + `//span[text()="` + label +
+			`"]/following-sibling::span[text()="` + value + `"]`
+	}
+
+	require.NoError(t, chromedp.Run(ctx, loadPage(url)))
+
+	assert.Truef(t, shown(ctx, figure("Delivered:", delivered)),
+		"the row of %s does not show %q delivered", name, delivered)
+	assert.Truef(t, shown(ctx, figure("Failed:", failed)),
+		"the row of %s does not show %q failed", name, failed)
+}
+
 // checkCopy loads a webhook page and checks that the Copy control beside
 // its entrypoint's URL is a button, and that clicking it copies the URL
 // and says so: the button reads "Copied" only once the copy succeeded.