feat: icon-only toolbar, versioning fixes, history modal, PanelRight repositioning

- Toolbar: remove text labels from all icon buttons (AI, Save, Preview, Convert)
  all buttons now icon-only with title tooltip for accessibility
- Toolbar: reposition PanelRight (info panel toggle) to far right after three-dot menu
- Versioning: decouple getNoteHistory/restoreNoteVersion from global userAISettings.noteHistory
  now checks note.historyEnabled directly — unblocks manual per-note history
- Versioning: add 'Sauvegarder cette version' button in Versions tab of info panel
  calls commitNoteHistory with visual feedback (spinner → success state)
- note-document-info-panel: import commitNoteHistory, add isSavingVersion state
- notes.ts: fix double guard that silently blocked all history operations

memento-note/components/notification-panel.tsx

@@ -142,21 +142,16 @@ export function NotificationPanel() {
   return (
     <Popover open={open} onOpenChange={setOpen}>
       <PopoverTrigger asChild>
-        <Button
-          variant="ghost"
-          size="sm"
-          className="relative h-9 w-9 p-0 hover:bg-accent/50 transition-all duration-200"
+        <button
+          className="relative h-9 w-9 flex items-center justify-center rounded-full bg-white border border-border text-muted-foreground hover:text-foreground hover:bg-white/40 transition-all"
         >
           <Bell className="h-4 w-4 transition-transform duration-200 hover:scale-110" />
           {pendingCount > 0 && (
-            <Badge
-              variant="destructive"
-              className="absolute -top-1 -right-1 h-5 w-5 flex items-center justify-center p-0 text-xs animate-pulse shadow-lg"
-            >
+            <span className="absolute -top-1 -right-1 h-4 w-4 flex items-center justify-center rounded-full bg-rose-500 text-white text-[9px] font-bold border border-white shadow-sm">
               {pendingCount > 9 ? '9+' : pendingCount}
-            </Badge>
+            </span>
           )}
-        </Button>
+        </button>
       </PopoverTrigger>
       <PopoverContent align="end" className="w-80 p-0">
         <div className="px-4 py-3 border-b bg-gradient-to-r from-primary/5 to-primary/10 dark:from-primary/10 dark:to-primary/15">