Manage registrations, Users, Events and Reports: save the current
filters under a name, apply one with a click, star one as the default
for the page (not applied over a deep link). Per person, stored on the
server, removed when an account is anonymised. /api/saved-filters.
Migration 20261028180000_saved_filters. Completes roadmap section 9.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>