First-pass CSV-to-JSON test: use a tricky harmless row

Before converting a large CSV, test a short sample with the same delimiter, headers, quoted fields, Unicode, and blank cells as the real file. Include a leading-zero ID to reveal unwanted numeric coercion. Check the JSON parses, object count matches rows, and values map to the correct keys. If the result is wrong, fix delimiter or type settings before processing the full dataset. Recheck the final output separately.