Ensure that the parent's hash is consistently named 'parent_hash' throughout the codebase to avoid potential confusion with older references such as 'parenthash'.

              Ensure that the parent's hash is consistently named 'parent_hash' throughout the codebase to avoid potential confusion with older references such as 'parenthash'.

_Originally posted by @Copilot in https://github.com/R-Computing-Lab/ggpedigree/pull/3#discussion_r2091946173_
            