向上滚动无限加载use-infinite-scroll的源码内部缺少了对滚动原点的判断

当滚动容器的el.style.flexDirection = 'column-reverse'时，滚动容器的滚动原点是从底部开始计算的，并且数值是负数，我看源码内部没有考虑这种情况，我自己封装无限滚动的时候，发现了这种情况。

Start by locating the use-infinite-scroll hook and reproduce the reported case with a scroll container using flexDirection = 'column-reverse'. Trace how the hook interprets the scroll origin and negative scroll values, then verify that upward infinite loading still triggers correctly in this configuration.

Written by the indexing model from the issue text.