fix(ux-audit): CRITICAL + HIGH fixes — a11y, reduced-motion, forms, keyboard nav

Global (globals.css):
- prefers-reduced-motion: désactive toutes les animations/transitions
- focus-visible:ring global sur tous les éléments interactifs

Search modal:
- role="dialog" + aria-modal="true" + aria-label
- onClick backdrop ferme la modale

Insights peek:
- DOMPurify.sanitize() sur dangerouslySetInnerHTML (XSS fix)

Login form:
- autoComplete="email" / "current-password"
- htmlFor sur tous les labels

Register form:
- autoComplete="name" / "email" / "new-password"
- htmlFor sur tous les labels

GridCard (notes-list-views):
- Actions visibles sur mobile (opacity-100 sm:opacity-0)
- aria-sort sur colonne triable
- role="button" + tabIndex + onKeyDown sur lignes table

Editorial view:
- role="button" + tabIndex + onKeyDown sur articles
- Menu trigger aria-label + visible mobile

Toolbar:
- aria-label voice i18n

memento-note/components/notes-list-views.tsx

@@ -385,6 +385,7 @@ export function NotesListViews({
                 <th
                   className="w-[18%] px-4 py-3 text-[10px] uppercase tracking-widest font-black text-muted-foreground cursor-pointer hover:text-foreground"
                   onClick={() => handleSort('modified')}
+                  aria-sort={sortColumn === 'modified' ? (sortDirection === 'asc' ? 'ascending' : 'descending') : 'none'}
                 >
                   <span className="inline-flex items-center gap-1">
                     {t('notes.tableModified')} <SortIcon field="modified" />
@@ -401,7 +402,10 @@ export function NotesListViews({
                   <tr
                     key={note.id}
                     onClick={() => onOpen(note)}
-                    className="h-11 hover:bg-foreground/[0.02] cursor-pointer transition-colors group"
+                    onKeyDown={(e) => { if (e.key === 'Enter') onOpen(note) }}
+                    tabIndex={0}
+                    role="button"
+                    className="h-11 hover:bg-foreground/[0.02] cursor-pointer transition-colors group focus-visible:bg-foreground/[0.04]"
                   >
                     <td className="px-4 py-2 font-memento-serif text-[13px] font-medium truncate max-w-[280px]">
                       <span className="inline-flex items-center gap-2 truncate group-hover:text-brand-accent transition-colors">
@@ -781,7 +785,7 @@ const GridCard = memo(function GridCard({
         </div>
         <div className="flex items-center justify-between pt-3 mt-auto border-t border-foreground/[0.03] dark:border-white/[0.03] text-[9.5px] text-muted-foreground font-medium uppercase tracking-wider">
           <span>{formattedDate}</span>
-          <div className="flex items-center gap-1 opacity-0 group-hover/card:opacity-100 transition-opacity">
+          <div className="flex items-center gap-1 opacity-100 sm:opacity-0 sm:group-hover/card:opacity-100 transition-opacity">
             <button
               type="button"
               onClick={handleBrainstormClick}