fix(ux-audit): landing next/image + confirm AlertDialog + search-modal i18n

Landing page:
- <img> → next/image avec width/height (CLS fix)
- padding nav responsive px-4 sm:px-8

note-card:
- confirm() natif → AlertDialog (non-bloquant, stylable)
- showLeaveDialog state + dialog component

search-modal (20 chaînes FR → i18n):
- useLanguage ajouté
- 20 strings FR hardcoded → t('searchModal.*')
- Clés ajoutées dans en.json + fr.json

memento-note/components/note-card.tsx

@@ -185,6 +185,7 @@ export const NoteCard = memo(function NoteCard({
   const [isDeleting, setIsDeleting] = useState(false)
   const [isHidden, setIsHidden] = useState(false)
   const [showDeleteDialog, setShowDeleteDialog] = useState(false)
+  const [showLeaveDialog, setShowLeaveDialog] = useState(false)
   const [showCollaboratorDialog, setShowCollaboratorDialog] = useState(false)
   const [collaborators, setCollaborators] = useState<any[]>([])
   const [owner, setOwner] = useState<any>(null)
@@ -408,14 +409,13 @@ export const NoteCard = memo(function NoteCard({
   }
 
   const handleLeaveShare = async () => {
-    if (confirm(t('notes.confirmLeaveShare'))) {
-      try {
-        await leaveSharedNote(note.id)
-        setIsDeleting(true) // Hide the note from view
-      } catch (error) {
-        console.error('Failed to leave share:', error)
-      }
+    try {
+      await leaveSharedNote(note.id)
+      setIsDeleting(true)
+    } catch (error) {
+      console.error('Failed to leave share:', error)
     }
+    setShowLeaveDialog(false)
   }
 
   const handleRemoveFusedBadge = async (e: React.MouseEvent) => {
@@ -657,7 +657,7 @@ export const NoteCard = memo(function NoteCard({
             className="h-6 px-2 text-xs text-gray-500 hover:text-red-600 dark:hover:text-red-400"
             onClick={(e) => {
               e.stopPropagation()
-              handleLeaveShare()
+              setShowLeaveDialog(true)
             }}
           >
             <LogOut className="h-3 w-3 me-1" />
@@ -885,6 +885,24 @@ export const NoteCard = memo(function NoteCard({
           </AlertDialogFooter>
         </AlertDialogContent>
       </AlertDialog>
+
+      {/* Leave Share Confirmation Dialog */}
+      <AlertDialog open={showLeaveDialog} onOpenChange={setShowLeaveDialog}>
+        <AlertDialogContent>
+          <AlertDialogHeader>
+            <AlertDialogTitle>{t('notes.leaveShare')}</AlertDialogTitle>
+            <AlertDialogDescription>
+              {t('notes.confirmLeaveShare')}
+            </AlertDialogDescription>
+          </AlertDialogHeader>
+          <AlertDialogFooter>
+            <AlertDialogCancel>{t('common.cancel')}</AlertDialogCancel>
+            <AlertDialogAction variant="destructive" onClick={handleLeaveShare}>
+              {t('notes.leaveShare')}
+            </AlertDialogAction>
+          </AlertDialogFooter>
+        </AlertDialogContent>
+      </AlertDialog>
     </Card>
   )
 })