Fix sprite alignment to grid coordinates to be more balanced

There's an annoying issue where the left-bottom corner of the sprite is considered its origin. So when you move left, all you need to do is dip a toe in the next square and you're considered part of that grid coord. If you move right you need your entire sprite to move over before you're considered a part of that coord. Ideally it'd be more like 50% of your sprite needs to be in a square in order to be considered in it.  _Originally posted by @mpwoz in https://github.com/4D4XFUN/bevy-jam-5/issues/22#issuecomment-2242202078_