fix(workspace): make note editor use full available width instead of centering at max-w-4xl

frontend/src/features/workspace/DocumentEditor.tsx

@@ -1403,7 +1403,7 @@ export const DocumentEditor: React.FC<DocumentEditorProps> = ({
       )}
 
       {/* Main Content Area */}
-      <div className="max-w-4xl w-full mx-auto px-4 sm:px-8 py-5 flex-1">
+      <div className="w-full px-4 sm:px-8 py-5 flex-1">
         {zoomedBlock ? (
           /* =========================================================================
              FOKUS-MODUS & ZOOM-IN (HOISTED SUBTREE VIEW)