Add a 'Refine ▾' toggle to the gallery filter bar that expands a full-width
GalleryFacetPanel below it, inside the same sticky hazey chrome. The panel
offers platform chips (with live counts + a 'No platform' unsourced bucket),
two count-badged curation-flag toggles (Untagged / No artist), and a from/to
date range bounded by the facet min/max.
Store gains the platform/untagged/no_artist/date_from/date_to filter params
(URL-mirrored, AND-composed) and a panel-gated, single-flighted loadFacets()
that fetches /api/gallery/facets scoped to the active filter. Shared
cloneFilter/filterToQuery helpers keep the bar and panel writing one URL
format. The panel auto-opens on deep-link when refine filters are present and
refetches counts (debounced) on every filter change.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
