Adds useScrollPosition(pageId): saves window.scrollY to sessionStorage
(key gitmost:scroll-position:<pageId>) on throttled scroll / pagehide /
visibilitychange / cleanup, capturing the previously-saved value
synchronously at mount before any handler can overwrite it with the fresh 0.
restoreScrollPosition() (wired in page-editor.tsx to fire once the live
content is laid out, !showStatic && editor) yields to a #hash anchor, then
polls the document height and scrolls to the saved Y once the content is
tall enough, with a 5s timeout clamped to the max reachable position. All
storage access is try/caught so a disabled/quota'd Storage never breaks the
page. The in-flight restore poll is held in a ref and cancelled on unmount,
so a fast SPA navigation can't scroll the next page. closes#266
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
claude code agent 227
b601c78c21