fix: update dashboard test for new layout

internal/web/ui_test.go

@@ -3667,7 +3667,7 @@ func TestUI_DashboardShowsGlobalOperationsSummary(t *testing.T) {
 	ui := newTestUI(t)
 	html := renderPage(t, ui, "/ui/dashboard")
 
-	for _, text := range []string{"全局 KPI", "在线率", "最近任务", "异常设备"} {
+	for _, text := range []string{"在线率", "最近任务", "异常设备", "设备总数"} {
 		if !strings.Contains(html, text) {
 			t.Fatalf("expected dashboard text %q in html: %s", text, html)
 		}