Improve fading for action tooltips

[Greenheart]

fade in/out after a threshold instead on based on total distance.

The fade does not look as good in the center, so we should experiment with removing it completely up until a threshold. Then fade in/out with a transition duration of x ms instead of fading based on distance.

Another point to consider: On small screens, the tooltip has to be shown closer to the middle so players have a chance to read it before they reach the SWIPE_THRESHOLD where they might accidently drop the card and trigger a swipe when just reading the action description.

Ideally, we'll find a good balance here.