docs: def imagej_metadata(self):
          """Return consolidated ImageJ metadata as dict."""
          if not self.is_imagej:
              return None
          page = self.pages[0]
          result = imagej_description_metadata(page.is_imagej)
          if 'IJMetadata' in page.tags:
              try:
                  result.update(page.tags['IJMetadata'].value)
              except Exception:
                  pass
          return result