Add sidebar TOC, simplify Données Secondaires section

- Rename 'Éditer Données Secondaires' → 'Données Secondaires', remove fieldset wrapper on Mots-clés link
- Create admin-toc.php partial: IntersectionObserver-based sidebar nav
- Include TOC on contenus.php, acces.php, parametres.php
- Add .admin-with-toc flex layout (sidebar + main) and .admin-toc CSS
- Fonts (Ductus, BBB DM Sans): verified loaded via variables.css → common.css import chain
- TOC: move inside <main> as <aside>, content in <article>, fix scrolling
- Lazy load: hx-trigger='load delay:100ms' with spinner (htmx-indicator) for tags/langues
- Inline rename: edit button in Nom cell, HTMX post for rename, validate+ cancel buttons
- Checkbox column: width:1% / fit-content
- Remove per-row merge forms/selects, only bulk merge when ≥2 checkboxes selected
- Remove per-row merge dialogs, keep only bulk merge and delete dialogs
- Add htmx-settling CSS transition for lazy-load fade-in
- Update acces.php/parametres.php: article layout, TOC inside main
- TOC: DOMContentLoaded guard, use <nav>+<a> directly instead of <ul>/<li>
- Section spacing: margin-bottom on sections and fieldsets in admin-main--toc
- Language dedup: GROUP BY LOWER(name) in getAllLanguagesWithCount and searchLanguages
- deduplicateLanguages() merges duplicate names and reassigns thesis_languages
- Sticky bulk-actions: position:sticky;top:0;z-index:10
- Tags toolbar: title left, stat count right (margin-left:auto), search bar under
- Tags count stat updated via hx-swap-oob from fragment
- Remove margin/max-width from .admin-main--toc
- Gap between TOC and article: --space-xs, sticky top: --space-xs
- Main padding: --space-s / --space-m / --space-xl (was --space-l/--space-l/--space-2xl)
- Article padding-top: --space-m

app/public/admin/contenus-langues-fragment.php

@@ -47,10 +47,10 @@ try {
 <table>
     <thead>
         <tr>
-            <th scope="col"><input type="checkbox" onchange="languesToggleAll(this)"></th>
+            <th scope="col" style="width:1%"><input type="checkbox" onchange="languesToggleAll(this)"></th>
             <th scope="col">Nom</th>
-            <th scope="col">TFE Associé</th>
-            <th scope="col">Actions</th>
+            <th scope="col" style="width:1%;white-space:nowrap">TFE Associé</th>
+            <th scope="col" style="width:1%">Actions</th>
         </tr>
     </thead>
     <tbody>
@@ -59,42 +59,17 @@ try {
         <?php else: ?>
         <?php foreach ($languages as $lang): ?>
         <tr>
-            <td><input type="checkbox" name="selected_langs[]" value="<?= (int)$lang['id'] ?>" onchange="languesUpdateBulk()"></td>
-            <td><?= htmlspecialchars($lang['name']) ?></td>
-            <td class="admin-tags-count"><?= (int)$lang['thesis_count'] ?></td>
-            <td class="admin-actions-col">
+            <td style="width:1%"><input type="checkbox" name="selected_langs[]" value="<?= (int)$lang['id'] ?>" onchange="languesUpdateBulk()"></td>
+            <td id="lang-name-<?= (int)$lang['id'] ?>" data-name="<?= htmlspecialchars($lang['name']) ?>">
+                <span class="tag-name-cell"><?= htmlspecialchars($lang['name']) ?></span>
+                <button type="button" class="admin-icon-btn admin-icon-btn--edit" title="Renommer"
+                        onclick="languesStartRename(<?= (int)$lang['id'] ?>)">
+                    <svg xmlns="http://www.w3.org/2000/svg" width="32" height="32" fill="currentColor" viewBox="0 0 256 256"><path d="M248,92.68a15.86,15.86,0,0,0-4.69-11.31L174.63,12.68a16,16,0,0,0-22.63,0L123.57,41.11l-58,21.77A16.06,16.06,0,0,0,55.35,75.23L32.11,214.68A8,8,0,0,0,40,224a8.4,8.4,0,0,0,1.32-.11l139.44-23.24a16,16,0,0,0,12.35-10.17l21.77-58L243.31,104A15.87,15.87,0,0,0,248,92.68Zm-69.87,92.19L63.32,204l47.37-47.37a28,28,0,1,0-11.32-11.32L52,192.7,71.13,77.86,126,57.29,198.7,130ZM112,132a12,12,0,1,1,12,12A12,12,0,0,1,112,132Zm96-15.32L139.31,48l24-24L232,92.68Z"></path></svg>
+                </button>
+            </td>
+            <td class="admin-tags-count" style="width:1%;white-space:nowrap"><?= (int)$lang['thesis_count'] ?></td>
+            <td class="admin-actions-col" style="width:1%">
                 <div class="admin-actions">
-                    <form method="post" action="actions/language.php" class="admin-inline-form">
-                        <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION['csrf_token']) ?>">
-                        <input type="hidden" name="action" value="rename">
-                        <input type="hidden" name="return" value="/admin/contenus.php">
-                        <input type="hidden" name="language_id" value="<?= (int)$lang['id'] ?>">
-                        <input class="admin-input--inline" type="text" name="new_name"
-                               value="<?= htmlspecialchars($lang['name']) ?>" required>
-                        <button type="submit" class="admin-icon-btn admin-icon-btn--edit" title="Renommer">
-                            <svg xmlns="http://www.w3.org/2000/svg" width="32" height="32" fill="currentColor" viewBox="0 0 256 256"><path d="M248,92.68a15.86,15.86,0,0,0-4.69-11.31L174.63,12.68a16,16,0,0,0-22.63,0L123.57,41.11l-58,21.77A16.06,16.06,0,0,0,55.35,75.23L32.11,214.68A8,8,0,0,0,40,224a8.4,8.4,0,0,0,1.32-.11l139.44-23.24a16,16,0,0,0,12.35-10.17l21.77-58L243.31,104A15.87,15.87,0,0,0,248,92.68Zm-69.87,92.19L63.32,204l47.37-47.37a28,28,0,1,0-11.32-11.32L52,192.7,71.13,77.86,126,57.29,198.7,130ZM112,132a12,12,0,1,1,12,12A12,12,0,0,1,112,132Zm96-15.32L139.31,48l24-24L232,92.68Z"></path></svg>
-                        </button>
-                    </form>
-
-                    <form method="post" action="actions/language.php" class="admin-inline-form">
-                        <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION['csrf_token']) ?>">
-                        <input type="hidden" name="action" value="merge">
-                        <input type="hidden" name="return" value="/admin/contenus.php">
-                        <input type="hidden" name="source_id" value="<?= (int)$lang['id'] ?>">
-                        <select name="target_id" class="admin-select--inline" required>
-                            <option value="">— Fusionner dans… —</option>
-                            <?php foreach ($languages as $other): ?>
-                                <?php if ($other['id'] !== $lang['id']): ?>
-                                <option value="<?= (int)$other['id'] ?>"><?= htmlspecialchars($other['name']) ?></option>
-                                <?php endif; ?>
-                            <?php endforeach; ?>
-                        </select>
-                        <button type="button" class="admin-icon-btn admin-icon-btn--merge" title="Fusionner"
-                                onclick="return languesConfirmMerge(this)">
-                            <svg xmlns="http://www.w3.org/2000/svg" width="32" height="32" fill="currentColor" viewBox="0 0 256 256"><path d="M216,32H88a8,8,0,0,0-8,8V80H40a8,8,0,0,0-8,8V216a8,8,0,0,0,8,8H168a8,8,0,0,0,8-8V176h40a8,8,0,0,0,8-8V40A8,8,0,0,0,216,32ZM160,208H48V96H160Zm48-48H176V88a8,8,0,0,0-8-8H96V48H208Z"></path></svg>
-                        </button>
-                    </form>
-
                     <form method="post" action="actions/language.php" class="admin-inline-form">
                         <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION['csrf_token']) ?>">
                         <input type="hidden" name="action" value="delete">