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/src/Database.php

@@ -1265,23 +1265,25 @@ class Database
         $query = trim($query);
         if ($query === '') {
             $stmt = $this->pdo->query('
-                SELECT l.id, UPPER(SUBSTR(l.name,1,1)) || SUBSTR(l.name,2) as name,
+                SELECT MIN(l.id) as id,
+                       UPPER(SUBSTR(MIN(l.name),1,1)) || SUBSTR(MIN(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
-                GROUP BY l.id
-                ORDER BY thesis_count DESC, l.name COLLATE NOCASE
+                GROUP BY LOWER(l.name)
+                ORDER BY thesis_count DESC, LOWER(MIN(l.name)) COLLATE NOCASE
                 LIMIT 10
             ');
         } else {
             $stmt = $this->pdo->prepare('
-                SELECT l.id, UPPER(SUBSTR(l.name,1,1)) || SUBSTR(l.name,2) as name,
+                SELECT MIN(l.id) as id,
+                       UPPER(SUBSTR(MIN(l.name),1,1)) || SUBSTR(MIN(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 LOWER(?)
-                GROUP BY l.id
-                ORDER BY LOWER(l.name) = LOWER(?) DESC, thesis_count DESC, l.name COLLATE NOCASE
+                GROUP BY LOWER(l.name)
+                ORDER BY LOWER(MIN(l.name)) = LOWER(?) DESC, thesis_count DESC, LOWER(MIN(l.name)) COLLATE NOCASE
                 LIMIT 10
             ');
             $stmt->execute([$query . '%', $query]);
@@ -1294,17 +1296,51 @@ class Database
      */
     public function getAllLanguagesWithCount(): array
     {
+        // Group by lowercased name to deduplicate, keeping the first id
         $stmt = $this->pdo->query('
-            SELECT l.id, UPPER(SUBSTR(l.name,1,1)) || SUBSTR(l.name,2) as name,
+            SELECT MIN(l.id) as id,
+                   UPPER(SUBSTR(MIN(l.name),1,1)) || SUBSTR(MIN(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
-            GROUP BY l.id
-            ORDER BY l.name COLLATE NOCASE
+            GROUP BY LOWER(l.name)
+            ORDER BY LOWER(MIN(l.name)) COLLATE NOCASE
         ');
         return $stmt->fetchAll();
     }
 
+    /**
+     * Deduplicate languages: merge languages with the same lowercased name.
+     */
+    public function deduplicateLanguages(): void
+    {
+        $dupes = $this->pdo->query('
+            SELECT LOWER(name) as lname, MIN(id) as keep_id
+            FROM languages
+            GROUP BY LOWER(name)
+            HAVING COUNT(*) > 1
+        ')->fetchAll();
+
+        foreach ($dupes as $dup) {
+            $this->pdo->prepare('
+                INSERT OR IGNORE INTO thesis_languages (language_id, thesis_id)
+                SELECT ?, thesis_id FROM thesis_languages WHERE language_id IN (
+                    SELECT id FROM languages WHERE LOWER(name) = ? AND id != ?
+                )
+            ')->execute([$dup['keep_id'], $dup['lname'], $dup['keep_id']]);
+
+            $this->pdo->prepare('
+                DELETE FROM thesis_languages WHERE language_id IN (
+                    SELECT id FROM languages WHERE LOWER(name) = ? AND id != ?
+                )
+            ')->execute([$dup['lname'], $dup['keep_id']]);
+
+            $this->pdo->prepare('
+                DELETE FROM languages WHERE LOWER(name) = ? AND id != ?
+            ')->execute([$dup['lname'], $dup['keep_id']]);
+        }
+    }
+
     /**
      * Rename a language. Throws if the new name already exists.
      */