fix: string values starting with \n exported as invalid YAML literal block

[KaracaerFurkan]

String fields whose value starts with a newline (e.g. expression values) were exported with a |4 literal block indicator, producing invalid YAML that caused the linter to crash with Error parsing YAML file.

Root cause: after indent-stripping, the leading \n was still present, triggering the multiline code path even when the actual content is a single line. The fix trims leading newlines before the multiline check so these values are exported as plain scalars.

[xiwenc]

thanks Furkan!

This does indeed solve your specific case. Will accept it for now. Will look into this in more detail to have a more structural solution that works in "all" cases.