Add accordion + active-filter chip bar for mobile repertoire

- 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

app/templates/partials/repertoire-index.php

@@ -106,9 +106,50 @@ foreach ($filterColumns as $col) {
         fn($i) => $i['matched']
     ));
 }
+
+// ── Active filter chips ─────────────────────────────────────────────────────
+// Build a flat list of {dim, label, value, url} for every active filter entry.
+$activeChips = [];
+$dimLabels = [
+    'years' => 'Année',
+    'ap'    => 'AP',
+    'or'    => 'Orientation',
+    'fi'    => 'Finalité',
+    'kw'    => 'Mot-clé',
+];
+foreach (['years', 'ap', 'or', 'fi', 'kw'] as $dim) {
+    foreach ($activeSets[$dim] as $val) {
+        $activeChips[] = [
+            'dim'   => $dim,
+            'label' => $dimLabels[$dim],
+            'value' => $val,
+            'url'   => repToggleUrl($activeSets, $dim, $val),
+        ];
+    }
+}
 ?>
 <div id="repertoire-index" class="repertoire-index">
 
+<?php if ($anyActive): ?>
+    <!-- Active filter chips bar -->
+    <div class="rep-chip-bar" role="status" aria-label="Filtres actifs">
+        <span class="rep-chip-bar__label">Filtres&nbsp;:</span>
+        <?php foreach ($activeChips as $chip): ?>
+        <button type="button" class="rep-chip"
+                hx-get="<?= htmlspecialchars($chip['url']) ?>"
+                hx-target="#repertoire-index"
+                hx-swap="outerHTML"
+                hx-push-url="true"
+                hx-indicator="#rep-indicator"
+                aria-label="Retirer le filtre <?= htmlspecialchars($chip['label']) ?> : <?= htmlspecialchars($chip['value']) ?>">
+            <span class="rep-chip__dim"><?= htmlspecialchars($chip['label']) ?></span>
+            <span class="rep-chip__value"><?= htmlspecialchars($chip['value']) ?></span>
+            <span class="rep-chip__remove" aria-hidden="true">×</span>
+        </button>
+        <?php endforeach; ?>
+    </div>
+<?php endif; ?>
+
 <?php
 // Render filter columns in the correct left-to-right order.
 // Students column (non-filter) is inserted between keywords and AP/or/fi/years.
@@ -117,8 +158,15 @@ $renderOrder = ['years', 'ap', 'or', 'fi', 'students', 'kw'];
 foreach ($renderOrder as $colKey):
     if ($colKey === 'students'): ?>
     <!-- ÉTUDIANTES -->
-    <section class="repertoire-col" data-col="students">
-        <h2>Étudiant·es</h2>
+    <section class="repertoire-col rep-accordion" data-col="students">
+        <h2>
+            <span class="rep-accordion__heading-text">Étudiant·es</span>
+            <button type="button" class="rep-accordion__toggle" aria-expanded="false">
+                Étudiant·es
+                <span class="rep-accordion__chevron" aria-hidden="true"></span>
+            </button>
+        </h2>
+        <div class="rep-accordion__panel">
         <ul>
         <?php if (empty($studentWorks)): ?>
             <li class="rep-empty">—</li>
@@ -143,16 +191,32 @@ foreach ($renderOrder as $colKey):
             <?php endforeach; ?>
         <?php endif; ?>
         </ul>
+        </div>
     </section>
 <?php else:
-        $col = array_values(array_filter($filterColumns, fn($c) => $c['dim'] === $colKey))[0]; ?>
-    <section class="repertoire-col" data-col="<?= $col['dim'] ?>">
-        <h2><?= $col['heading'] ?></h2>
+        $col = array_values(array_filter($filterColumns, fn($c) => $c['dim'] === $colKey))[0];
+
+        // Count active filters in this column for the badge
+        $activeCount = count($activeSets[$col['dim']]);
+        ?>
+    <section class="repertoire-col rep-accordion" data-col="<?= $col['dim'] ?>">
+        <h2>
+            <span class="rep-accordion__heading-text"><?= $col['heading'] ?></span>
+            <button type="button" class="rep-accordion__toggle" aria-expanded="false">
+                <?= $col['heading'] ?>
+                <?php if ($activeCount > 0): ?>
+                <span class="rep-accordion__badge"><?= $activeCount ?></span>
+                <?php endif; ?>
+                <span class="rep-accordion__chevron" aria-hidden="true"></span>
+            </button>
+        </h2>
+        <div class="rep-accordion__panel">
         <ul>
 <?php   foreach ($repData[$col['dataKey']] as $item):
             repFilterEntry($item, $col['dim'], $activeSets, $anyActive, $colHasMatches[$col['dim']], $hx);
         endforeach; ?>
         </ul>
+        </div>
     </section>
 <?php endif;
 endforeach; ?>