Expose clearUndoRedo

[mfaux]

Currently, to clear the undo/redo stack, I need to access a protected field:

export function clearUndoRedoStack(api: FUniver, workbookId: string): void {
  try {
    // Access the undoRedoService via dependency injection.
    // Univer's facade (FUniver/FWorkbook) does not expose a public clearUndoRedo helper,
    // so this internal service call is currently the only way to reset the stack.
    // @ts-expect-error - Accessing protected _injector field to reach internal services
    const injector = api._injector;
    const undoRedoService = injector.get(IUndoRedoService);
    undoRedoService.clearUndoRedo(workbookId);
  } catch (error) {
    log.warn('failed to clear undo/redo stack', { workbookId, error });
  }
}

Consider exposing clearUndoRedo via the Facade API.

I need this functionality in order to prevent users from undoing things like sheet protection and data validations. For example, I can make my sheet header read-only when I insert it programmatically, but the user can CTRL-z and remove that protection.