Function format_csv 

pub fn format_csv(
    result: ProcessedResult,
    include_header: bool,
) -> Result<Vec<u8>, SofError>

Encodes a ProcessedResult as CSV bytes via the csv crate (RFC 4180).

String values are emitted raw; non-string values are JSON-serialised. The underlying writer handles quoting for fields containing ,, ", or newlines, so callers do not need to escape.