Filters/sort/search/scope were written to the address bar on every change (a leftover
from sharing reproducible examples), giving two sources of truth. Make localStorage the
single source: drop the automatic syncUrl from setFilters/setPage. A "Share view" link
still hydrates filters on first load, after which the query is stripped from the URL
(stripUrlParams) so it stays clean. syncUrl is replaced by shareUrl (builds the link on
demand); the serializer now also round-trips scope.