fix: i18n complet — mobile, backlinks, undo/redo, content-area

- mobile-action-sheet.tsx: 15 chaînes → t()
- wikilinks-backlinks-panel.tsx: 3 chaînes → t() + import useLanguage
- note-content-area.tsx: 'Cliquez pour éditer' → t()
- undo-redo-feedback-extension.ts: strings → options configurables
- i18n FR/EN: 11 nouvelles clés (mobile.*, editor.*)
- SlashPreview et SlashCommand: déjà OK (i18n via localCommands)

memento-note/components/wikilinks-backlinks-panel.tsx

@@ -5,6 +5,7 @@ import { Link2, ChevronRight, Loader2 } from 'lucide-react'
 import { cn } from '@/lib/utils'
 import { motion, AnimatePresence } from 'motion/react'
 import { useRouter } from 'next/navigation'
+import { useLanguage } from '@/lib/i18n'
 
 interface BacklinkNote {
   id: string
@@ -26,6 +27,7 @@ interface WikilinksBacklinksPanelProps {
 }
 
 export function WikilinksBacklinksPanel({ noteId, className }: WikilinksBacklinksPanelProps) {
+  const { t } = useLanguage()
   const [backlinks, setBacklinks] = useState<Backlink[]>([])
   const [loading, setLoading] = useState(true)
   const [open, setOpen] = useState(true)
@@ -54,7 +56,7 @@ export function WikilinksBacklinksPanel({ noteId, className }: WikilinksBacklink
       >
         <Link2 size={14} className="text-concrete shrink-0" />
         <span className="text-[10px] uppercase tracking-[0.25em] font-bold text-concrete group-hover:text-ink transition-colors">
-          Liens entrants
+          {t('editor.backlinks') || 'Liens entrants'}
         </span>
         <span className="text-[9px] bg-brand-accent/10 text-brand-accent px-1.5 py-0.5 rounded-full font-bold">
           {backlinks.length}
@@ -78,7 +80,7 @@ export function WikilinksBacklinksPanel({ noteId, className }: WikilinksBacklink
             {loading && (
               <div className="flex items-center gap-2 py-2">
                 <Loader2 size={12} className="animate-spin text-concrete" />
-                <span className="text-[10px] text-concrete">Chargement…</span>
+                <span className="text-[10px] text-concrete">{t('common.loading') || 'Chargement…'}</span>
               </div>
             )}
             {backlinks.map(bl => (
@@ -92,7 +94,7 @@ export function WikilinksBacklinksPanel({ noteId, className }: WikilinksBacklink
                   <Link2 size={10} className="text-brand-accent/60 mt-0.5 shrink-0" />
                   <div className="min-w-0 flex-1">
                     <p className="text-[11px] font-semibold text-ink truncate group-hover/bl:text-brand-accent transition-colors">
-                      {bl.sourceNote.title || '(Sans titre)'}
+                      {bl.sourceNote.title || (t('notes.untitled') || '(Sans titre)')}
                     </p>
                     {bl.contextSnippet && (
                       <p className="text-[9px] text-concrete/70 mt-0.5 line-clamp-2 leading-relaxed">