Import Validation Issue Message

The message on an ImportValidationIssue is what compliance staff read first when triaging a batch's problems. It translates a technical validation failure into plain language — for example, "Analyte code 'BENZEN' was not found in the analyte registry" or "sampleDate is not a valid date." The message works together with the field, value, and suggestion fields to give a reviewer all the information needed to resolve the issue or escalate it to the laboratory for clarification.