feat: notes encore plus larges — max-w-6xl body + font 18px

Full page editor:
- Container: max-w-5xl → max-w-6xl (1024px → 1152px)
- Content: max-w-4xl → max-w-5xl (896px → 1024px)
- Toolbar: max-w-5xl → max-w-6xl (aligné)

Dialog editor:
- max-w 1800px → 2000px, 97vw → 98vw
- Hauteur 92vh → 94vh

Font editor:
- editor-body-size: 16px → 18px (lecture plus confortable)

memento-note/components/note-editor/note-editor-toolbar.tsx

@@ -530,7 +530,7 @@ export function NoteEditorToolbar({ mode, onClose, onToggleAttachments, attachme
     }
 
     return (
-      <div className="max-w-5xl mx-auto w-full px-4 sm:px-8 md:px-12 py-4 sm:py-6 md:py-8 flex items-center justify-between sticky top-0 bg-white/95 dark:bg-background/95 backdrop-blur-sm z-40 border-b border-border dark:border-white/10">
+      <div className="max-w-6xl mx-auto w-full px-4 sm:px-8 md:px-12 py-4 sm:py-6 md:py-8 flex items-center justify-between sticky top-0 bg-white/95 dark:bg-background/95 backdrop-blur-sm z-40 border-b border-border dark:border-white/10">
         <button
           onClick={handleCloseWithSave}
           className="flex items-center gap-2 text-foreground hover:opacity-60 transition-opacity"