SheetContent
data class SheetContent(@ColorInt val backgroundColor: Int, val title: InAppText?, val message: InAppText?, val imageUrl: String?, val showCloseButton: Boolean, val buttons: List<InAppButton>, val dimsBackground: Boolean)
Same field-for-field shape as ModalContent: the contract's sheet and modal blocks differ only in how the card is laid out (bottom-pinned with a grabber vs. centered).