perf: replace manual fireEvent loop with shared wrapFireEventMethods

[Lojhan]

Summary

Replaces the manual for loop in react-testing.ts with the new wrapFireEventMethods() helper exported by @pokujs/dom.

Before

~20 lines of boilerplate that iterated Object.keys(baseFireEventInstance), copied non-function properties as-is, and wrapped functions with an act() call.

After

wrapFireEventMethods(
  wrappedFireEvent as unknown as Record<string, unknown>,
  baseFireEventInstance as unknown as Record<string, unknown>,
  (invoke: () => unknown) => {
    let result: unknown;
    act(() => { result = invoke(); });
    return result;
  }
);

Behaviour is identical — act() still wraps every dispatched event. The change eliminates duplicated boilerplate that is now shared with @pokujs/vue.