Before-and-after CSV-to-JSON review: compare keyed records

Compare the source CSV and converted JSON using a stable row identifier, not only position. Verify header mapping, object count, quoted commas, embedded newlines, blank cells, and type inference. A value such as 0012 may become 12 if interpreted numerically; that is a data change even if the JSON parses. Record the intended treatment of empty versus null. Inspect both raw files so spreadsheet display rules do not obscure the difference.