Bad initialization in example code, should not be in the build() function

The [example code](https://github.com/amondnet/flutter_uxcam?tab=readme-ov-file#example) is plain and simple, but it has an issue. The initialization is made in the build() function. The build() function is supposed to be free of any side effects. You have to put the initialization in a function that will be ran only once.

In this example it's the top level `StatelessWidget`, so it will not actually rebuild in regular use. However, it will surely rebuild during development when you do a hot reload. So every time a Flutter dev saves the file to hot reload the running application, your initialization code would run one more time, which is not good.

Please move the initialization code in the example to either the `main()` function or make your `MainApp` a `StatefulWidget` and move it to its `initState()` function.