Fix some features and styles that don't work properly on some devices

[ShiYioo]

Your tutorial and solution code doesn't seem to work on my emulator, your code may not work properly on some devices or other factors, I try to fix it and give a new solution code

When I try to enter values in the keyboard, it seems to generate a lot of GameViewModel instances on the run, and the init block keeps running, all of which I set to singleton mode

The gameUiState variable declared by val in GameScreen.kt, my Android Studio tells me that it can't pass by delegate, I've tried to fix it and it works perfectly

Also, I fixed some styling bugs in the tutorial，modifier = modifier.align(Alignment.CenterHorizontally) is changed to modifier = Modifier.align(Alignment.CenterHorizontally)

[google-cla]

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