Scroll-position restore was never implemented (only a TODO in nav.rs);
back/forward tracked which page was visited, not where it was scrolled.
Add per-history-entry scroll memory: the mounted scroll container reports
its live viewport-y via NavState.report-scroll, so every navigation (fresh
record + back/forward) stamps the outgoing entry without touching the ~30
record call sites. go_back/go_forward hand the saved scroll back to the
shell, which arms NavState.restore-scope + scroll-restore before switching
the view. A container restores only when its scope matches, once per mount,
and only after content has laid out (viewport overflows) to dodge the
clamp-to-0 on async data load; it clears the scope once consumed.
Wired the four Local Library lists (albums, tracks, folders, artists rail).
Tracks is paginated, so its restore is best-effort within loaded pages.
cc
vicrodh
641aa22c17