The START button's enabled state is never updated when `IsLiveActivityUpdating` becomes true — `RefreshUpdateEndButtons()` correctly disables UPDATE and END during an in-flight async call, but `StartButton.IsEnabled` is only managed in `OnActivityIdChanged` based on text content alone. A user can tap START while an UPDATE or END REST call is in-flight, causing `StartDefault()` to be called on the SDK concurrently with an active update/end request for the same `activityId`. Fix by also incorporat

The [Obsolete] message 'Currently unsupported, avoid using this method.' on ILiveActivities.Exit() is factually inaccurate for iOS: iOSLiveActivitiesManager.Exit() is fully implemented and calls OneSignalNative.LiveActivities.Exit() with success/failure callbacks. A more accurate message would be 'Deprecated: use the REST API to end live activities instead.' since the PR's stated intent is to deprecate the method in favor of the REST API path, not to signal that the method does not work.