- repertoire-index.php: wrap each filter column in rep-accordion with toggle
button, chevron, badge (active filter count); add rep-chip-bar with
removable active-filter chips above the columns
- repertoire.css: mobile (≤640px) accordion mode — columns collapse to
single-open accordion sections with 48px touch targets; chip bar becomes
sticky; desktop/tablet layout unchanged via display:none on toggle elements
- repertoire.php: JS for single-accordion-open behavior on mobile, HTMX
re-init after swap, resize-breakpoint cleanup
- docs/repertoire-mobile-propositions.md: analysis + 4 architecture proposals
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