Add language-search component for Autre Langue input + active search in lists

Mirrors the mots-clé tag-search system: dropdown suggestions from
existing languages via HTMX, pill display with bin-icon remove buttons,
'Créer' option for new languages. Replaces the plain text input.

- New partial: templates/partials/form/language-search.php
- New fragment: public/partage/language-search-fragment.php
- Admin wrapper: public/admin/language-search-fragment.php
- Updated language-autre-fragment to return just the required asterisk indicator
- Updated both controllers to handle language_autre as array (pill-based)
  with backward-compatible string path
- Updated edit form to compute selectedOtherLanguages from DB
- Registered new route in partage/index.php
- Fix CSV importer: split comma-separated language column into individual entries
- Add htmx active search to admin index, title line-clamp, predefined languages only in checkboxes
- Admin index: filter form now uses htmx triggers (input delay:300ms on search,
  change on selects) to actively search without page reload
- Sort links include hx-push-url for back-button support
- Added loading indicator bar (.admin-search-indicator)
- Title column: line-clamp at 2 lines with overflow hidden, native title attr
  tooltip for full text
- Language checkboxes now show only 3 predefined languages (Français, Anglais,
  Néerlandais); all others go via the Autre langue search component
- Added Database::getPredefinedLanguages() and excluded predefined from
  language-search-fragment suggestions
- Included hidden sort/dir inputs in table-wrap so sort state preserved across
  filter changes
- Fix language-search: block 'Créer' for predefined languages in dropdown
  The 'Créer' option in the language-search dropdown now also checks against the
  predefined set (français, anglais, néerlandais) to avoid offering creation of
  languages that already exist as checkboxes.

app/public/partage/index.php

@@ -56,6 +56,13 @@ if ($slug === 'tag-search-fragment' && $_SERVER['REQUEST_METHOD'] === 'POST') {
     exit;
 }
 
+// Special route: /partage/language-search-fragment (HTMX fragment — interactive language search)
+if ($slug === 'language-search-fragment' && $_SERVER['REQUEST_METHOD'] === 'POST') {
+    App::boot();
+    require_once __DIR__ . '/language-search-fragment.php';
+    exit;
+}
+
 // Special route: /partage/recapitulatif?id=N
 if ($slug === 'recapitulatif' || $slug === 'recapitulatif.php') {
     App::boot();

app/public/partage/language-autre-fragment.php

@@ -2,9 +2,9 @@
 /**
  * language-autre-fragment.php
  *
- * Shared HTMX fragment include: returns the "Autre(s) langue(s)" input row
- * when no standard language checkbox is checked, or the plain (non-required)
- * variant when at least one is checked.
+ * Shared HTMX fragment include: returns the requirement asterisk for the
+ * "Autre(s) langue(s)" label. When no standard language checkbox is checked,
+ * an asterisk is rendered to signal the field is required (server-side validated).
  *
  * Included by:
  *   - /admin/language-autre-fragment.php  (AdminAuth gated)
@@ -12,25 +12,11 @@
  *
  * Expected POST:
  *   languages[]      — selected language IDs (may be absent)
- *   language_autre   — current free-text value (for repopulation)
  */
 
 $selectedIds  = isset($_POST['languages']) && is_array($_POST['languages'])
     ? $_POST['languages']
     : [];
-$currentValue = htmlspecialchars(trim($_POST['language_autre'] ?? ''));
 $anyChecked   = !empty($selectedIds);
 ?>
-<div id="language-autre-row">
-    <div>
-        <label for="language_autre">Autre(s) langue(s) :<?= !$anyChecked ? ' <span class="asterisk">*</span>' : '' ?></label>
-        <div>
-            <input type="text"
-                   id="language_autre"
-                   name="language_autre"
-                   value="<?= $currentValue ?>"
-                   <?= !$anyChecked ? 'required' : '' ?>>
-            <small>Si votre TFE contient une langue absente de la liste, précisez-la ici.</small>
-        </div>
-    </div>
-</div>
+<span id="language-autre-required"><?= !$anyChecked ? ' <span class="asterisk">*</span>' : '' ?></span>

app/public/partage/language-search-fragment.php

@@ -0,0 +1,107 @@
+<?php
+/**
+ * language-search-fragment.php
+ *
+ * Shared HTMX fragment: returns matching language suggestions for the
+ * "Autre(s) langue(s)" interactive search input.
+ *
+ * Included by:
+ *   - /admin/language-search-fragment.php  (AdminAuth gated)
+ *   - partage/index.php special route      (public, session already booted)
+ *
+ * Expected POST:
+ *   q                  — search query string (partial language name)
+ *   language_autre[]   — already selected language names (for exclusion)
+ */
+require_once __DIR__ . '/../../src/Database.php';
+
+$query = trim(preg_replace('/\s+/', ' ', strtolower($_POST['q'] ?? '')));
+$currentLanguages = isset($_POST['language_autre']) && is_array($_POST['language_autre'])
+    ? array_map(function($l) { return trim(preg_replace('/\s+/', ' ', strtolower($l))); }, $_POST['language_autre'])
+    : [];
+
+$db      = Database::getInstance();
+
+// Search existing languages by name, excluding predefined ones (already shown as checkboxes)
+$predefined = ["français", "anglais", "néerlandais", "francais", "neerlandais"];
+if ($query !== '') {
+    $placeholders = implode(',', array_fill(0, count($predefined), '?'));
+    $stmt = $db->getConnection()->prepare(
+        "SELECT l.id, UPPER(SUBSTR(l.name,1,1)) || SUBSTR(l.name,2) as name,
+                COUNT(DISTINCT tl.thesis_id) as thesis_count
+         FROM languages l
+         LEFT JOIN thesis_languages tl ON l.id = tl.language_id
+         WHERE LOWER(l.name) LIKE ?
+           AND LOWER(l.name) NOT IN ($placeholders)
+         GROUP BY l.id
+         ORDER BY LOWER(l.name) = ? DESC, thesis_count DESC, LOWER(l.name)
+         LIMIT 10"
+    );
+    $stmt->execute(array_merge([$query . '%'], $predefined, [$query]));
+} else {
+    $placeholders = implode(',', array_fill(0, count($predefined), '?'));
+    $stmt = $db->getConnection()->prepare(
+        "SELECT l.id, UPPER(SUBSTR(l.name,1,1)) || SUBSTR(l.name,2) as name,
+                COUNT(DISTINCT tl.thesis_id) as thesis_count
+         FROM languages l
+         LEFT JOIN thesis_languages tl ON l.id = tl.language_id
+         WHERE LOWER(l.name) NOT IN ($placeholders)
+         GROUP BY l.id
+         ORDER BY thesis_count DESC, LOWER(l.name)
+         LIMIT 10"
+    );
+    $stmt->execute($predefined);
+}
+
+$results = $stmt->fetchAll();
+
+// Deduplicate results by lowercase name
+$seen = [];
+$results = array_values(array_filter($results, function($lang) use (&$seen) {
+    $key = strtolower($lang['name']);
+    if (isset($seen[$key])) return false;
+    $seen[$key] = true;
+    return true;
+}));
+
+// Filter out already-selected languages (case-insensitive)
+$results = array_values(array_filter($results, function($lang) use ($currentLanguages) {
+    return !in_array(strtolower($lang['name']), $currentLanguages, true);
+}));
+
+// Check if query exactly matches an existing language (case-insensitive)
+// Also check against predefined languages to avoid suggesting creation of a checkbox language
+$exactExists = false;
+foreach ($results as $lang) {
+    if (strcasecmp($lang['name'], $query) === 0) {
+        $exactExists = true;
+        break;
+    }
+}
+if (!$exactExists && $query !== '') {
+    $normalisedQuery = strtolower($query);
+    $normalisedPredefined = array_map('strtolower', $predefined);
+    if (in_array($normalisedQuery, $normalisedPredefined, true)) {
+        $exactExists = true;
+    }
+}
+
+// If no exact match and query non-empty, suggest creation
+$canCreate = ($query !== '' && !$exactExists && !in_array($query, $currentLanguages, true));
+?>
+<?php if (empty($results) && !$canCreate): ?>
+<div class="tag-search-empty">Aucune langue trouvée.</div>
+<?php endif; ?>
+
+<?php foreach ($results as $lang): ?>
+<button type="button" class="tag-search-item" data-tag-id="<?= (int)$lang['id'] ?>" data-tag-name="<?= htmlspecialchars($lang['name']) ?>">
+    <span class="tag-search-item-name"><?= htmlspecialchars($lang['name']) ?></span>
+    <span class="tag-search-item-count">(<?= (int)$lang['thesis_count'] ?>)</span>
+</button>
+<?php endforeach; ?>
+
+<?php if ($canCreate): ?>
+<button type="button" class="tag-search-item tag-search-item--create" data-tag-name="<?= htmlspecialchars($query) ?>">
+    <span class="tag-search-item-name">Créer «&nbsp;<?= htmlspecialchars($query) ?>&nbsp;»</span>
+</button>
+<?php endif; ?>