Fix watchdog callout test act helper

ui/src/components/WatchdogStateCallout.test.tsx

@@ -1,7 +1,7 @@
 // @vitest-environment jsdom
 
-import { act } from "react";
 import type { ComponentProps, ReactNode } from "react";
+import { flushSync } from "react-dom";
 import { createRoot, type Root } from "react-dom/client";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
@@ -33,6 +33,14 @@ vi.mock("@/api/issues", () => ({
 let container: HTMLDivElement;
 let root: Root;
 
+function act(callback: () => void | Promise<void>) {
+  let result: void | Promise<void> | undefined;
+  flushSync(() => {
+    result = callback();
+  });
+  return result;
+}
+
 const summary: IssueWatchdogSummary = {
   id: "wd-1",
   companyId: "co-1",