In the same spirit as [[ https://code.wildfiregames.com/D982 | #D982 ]], fix something not really notifiable.
There are small slutterings when the Kushite background is scrolling.
Adding the `round_coordinates` attribute for all sprites fix it.
Also I move the offset of balcony a few pixels to display a bit more the guard.
(The balcony isn't fully displayed following the resolution of the user's screen maybe we can scale it a bit.)