Import Validation Issue

When Piper parses a lab file, it validates each row against expected formats, known analyte codes, required fields, and unit consistency. Any problem becomes an ImportValidationIssue linked to the batch via importBatchId. The severity tells you how urgent the issue is — error-level issues block the row from committing; warning-level issues allow commit but flag the row for review. The field and value fields identify exactly what was wrong in the original data, and the message explains it in plain language. If Piper can propose a fix, it records it in suggestion. A reviewer can accept that suggestion or enter their own overrideValue, then mark the issue resolved. Resolved issues record resolvedAt and resolvedBy for audit.