fix: tag settings nav items + dashboard quick help labels

- Settings sidebar: 6 items with emoji prefixes → data-i18n
- Settings content: 20+ section/label items tagged
- Dashboard quick help: section title + shortcut descriptions
- About modal: built-with section
- 233 total data-i18n attributes

frontend/index.html

@@ -1381,30 +1381,30 @@
                             </li>
                             <li>
                                 <a href="#cfg-sync" class="help-nav-link"
-                                    >🔄 Synchronisation</a
+                                     data-i18n="settings.sync">🔄 Synchronisation</a
                                 >
                             </li>
                             <li>
                                 <a href="#cfg-diags" class="help-nav-link"
-                                    >🩺 Diagnostics</a
+                                     data-i18n="settings.diagnostics">🩺 Diagnostics</a
                                 >
                             </li>
                             <li>
                                 <a href="#cfg-ai" class="help-nav-link"
-                                    >🤖 IA</a
+                                     data-i18n="settings.ai">🤖 IA</a
                                 >
                             </li>
                             <li>
                                 <a href="#cfg-profile" class="help-nav-link"
-                                    >👤 Profil</a
+                                     data-i18n="settings.profile">👤 Profil</a
                                 >
                             </li>
                             <li>
                                 <a href="#cfg-about" class="help-nav-link"
-                                    >📦 A propos</a
+                                     data-i18n="settings.about">📦 A propos</a
                                 >
                                 <a href="#cfg-themes" class="help-nav-link"
-                                    >🎨 Themes</a
+                                     data-i18n="settings.themes">🎨 Themes</a
                                 >
                             </li>
                         </ul>
@@ -3345,7 +3345,7 @@
                                 <li>
                                     <strong data-i18n="help.toolbar_section">Barre d'outils AI</strong> :
                                     Complétion, réécriture, traduction (voir
-                                    section <a href="#help-ia">🤖 IA</a>)
+                                    section <a href="#help-ia" data-i18n="settings.ai">🤖 IA</a>)
                                 </li>
                             </ul>
                         </section>