Compose Multiplatform UI utilities shared between paginator-compose-offset and paginator-compose-cursor. Contains the scroll-position preservation primitives (ScrollSnapshot data classes, ScrollSnapshotRegistry, internal save/restore composables) that back the `preserveScroll = true` parameter on BindToLazyList / BindToLazyGrid / BindToLazyStaggeredGrid, plus the shared scroll-binder core (BindScrollInternal) and PrefetchErrorChannel. Depends only on paginator-core (for the ScrollWindow ...