fix: add missing aria-labels to icon-only buttons for accessibility

- Sidebar close button: aria-label for screen readers
- Sidebar search clear button: aria-label
- ChatMessage raw JSON copy button: aria-label
- Added i18n keys: sidebar.close, sidebar.clearSearch (EN + FR)

src/components/ChatMessage.tsx

@@ -338,6 +338,7 @@ function RawJsonPanel({ message }: { message: ChatMessageType }) {
           onClick={handleCopy}
           className="h-6 w-6 rounded-md flex items-center justify-center text-pc-text-secondary hover:text-pc-accent-light transition-colors"
           title={copied ? t('message.copied') : t('message.copy')}
+          aria-label={copied ? t('message.copied') : t('message.copy')}
         >
           {copied ? <Check size={12} className="text-emerald-400" /> : <Copy size={12} />}
         </button>

src/components/Sidebar.tsx

@@ -181,7 +181,7 @@ export function Sidebar({ sessions, activeSession, onSwitch, onDelete, onSplit,
             </div>
             <span className="font-semibold text-sm text-pc-text tracking-wide">{t('sidebar.title')}</span>
           </div>
-          <button onClick={onClose} className="lg:hidden p-1.5 rounded-xl hover:bg-[var(--pc-hover)] text-pc-text-secondary transition-colors">
+          <button onClick={onClose} className="lg:hidden p-1.5 rounded-xl hover:bg-[var(--pc-hover)] text-pc-text-secondary transition-colors" aria-label={t('sidebar.close')}>
             <X size={16} />
           </button>
         </div>
@@ -204,6 +204,7 @@ export function Sidebar({ sessions, activeSession, onSwitch, onDelete, onSplit,
                 <button
                   onClick={() => updateFilter('')}
                   className="absolute right-2 top-1/2 -translate-y-1/2 text-pc-text-muted hover:text-pc-text"
+                  aria-label={t('sidebar.clearSearch')}
                 >
                   <X size={12} />
                 </button>

src/lib/i18n.ts

@@ -60,6 +60,8 @@ const en = {
   'sidebar.deleteConfirm': 'Delete this session? This cannot be undone.',
   'sidebar.deleteCancel': 'Cancel',
   'sidebar.openSplit': 'Open in split view',
+  'sidebar.close': 'Close sidebar',
+  'sidebar.clearSearch': 'Clear search',
   'split.close': 'Close split view',
 
   // Thinking
@@ -175,6 +177,8 @@ const fr: Record<keyof typeof en, string> = {
   'sidebar.deleteConfirm': 'Supprimer cette session ? Cette action est irréversible.',
   'sidebar.deleteCancel': 'Annuler',
   'sidebar.openSplit': 'Ouvrir en vue scindée',
+  'sidebar.close': 'Fermer la barre latérale',
+  'sidebar.clearSearch': 'Effacer la recherche',
   'split.close': 'Fermer la vue scindée',
 
   'thinking.label': 'Réflexion',