fix(virtual-core): sync `scrollOffset` in `applyScrollAdjustment` so end-anchored resize is not lost to browser clamp (#1209)

With `anchorTo: 'end'` and a dynamically growing last item, `resizeItem`
calls `applyScrollAdjustment` before `notify()`, so the `scrollTop` write
lands while the sizer is still at the old `getTotalSize()`. The browser
clamps the write, no scroll event fires, and `scrollOffset` stays stale.
The next tick's `getVirtualDistanceFromEnd()` then exceeds
`scrollEndThreshold`, `wasAtEnd` flips false, and the viewport drifts
away from the end from the second resize onward.

Carry the intended target in `scrollOffset` (and zero `scrollAdjustments`
to keep their sum invariant) the same way the prepend path in `setOptions`
does (#1176), so the next `wasAtEnd` check sees the post-adjustment
position regardless of whether the DOM write was clamped.