Import Batch File Size

The fileSize on an ImportBatch is stored for operational awareness and auditing. An unexpectedly small fileSize compared to typical lab deliverables from the same labName can signal a truncated or corrupted file before parsing even begins. Administrators monitoring import activity can use fileSize alongside totalRows to spot files where the size-to-row ratio seems anomalous, prompting a check before the batch is committed and results are written to the site record.