docs: def usable_location(self):
          """
          Returns:
              str | None: First available usable location
          """
          if self.file_location is not None:
              # Custom location typically provided via --config CLI flag
              return self._auto_complete_filename(self.file_location)
          if self.locations:
              for location in self.locations:
                  path = self._auto_complete_filename(location)
                  if path:
                      return path