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-full-page.tsx

@@ -72,8 +72,8 @@ export function NoteEditorFullPage({ onClose }: NoteEditorFullPageProps) {
           {/* TOOLBAR */}
           <NoteEditorToolbar mode="fullPage" onClose={onClose} onToggleAttachments={() => setUploadTrigger(v => v + 1)} attachmentsCount={attachmentsCount} />
 
-          {/* BODY — max-w-5xl, responsive px, py-16 */}
-          <div className="max-w-5xl mx-auto w-full px-6 sm:px-12 py-16 space-y-12 min-w-0">
+          {/* BODY — max-w-6xl, responsive px, py-16 */}
+          <div className="max-w-6xl mx-auto w-full px-6 sm:px-12 py-16 space-y-12 min-w-0">
 
             {/* Breadcrumb + Title block */}
             <div className="space-y-4">
@@ -130,8 +130,8 @@ export function NoteEditorFullPage({ onClose }: NoteEditorFullPageProps) {
               </div>
             )}
 
-            {/* Content area — max-w-4xl for wider reading column */}
-            <div className="max-w-4xl mx-auto w-full space-y-8 pb-32">
+            {/* Content area — max-w-5xl for wider reading column */}
+            <div className="max-w-5xl mx-auto w-full space-y-8 pb-32">
               {state.quotaExceededFeature === 'reformulate' && (
                 <InlinePaywall
                   feature="reformulate"