First-pass JSON-to-CSV test: use edge-case records

Before converting a large JSON set, try two or three harmless records with a missing field, Unicode text, a comma or quote, and a nested value. Confirm the header order, row count, raw CSV quoting, and how the target viewer displays values. If types matter, decide whether CSV is an appropriate lossier format for the handoff. Fix the mapping rule before processing real data, then validate the final export separately.