Append the audit-log request hash to a parallel-results frame
Source:R/LLM_parallel_utils.R
llm_add_request_hash.RdAdds a request_hash column to a data frame that still carries the config
and messages list-columns (such as the result of call_llm_par()). The
hash is the same key llm_request_hash() produces, so the parallel path can
be joined to the audit log written by llm_log_enable(). Equivalent to
calling call_llm_par(..., .request_hash = TRUE) after the fact.