calculate_total_row tested each column with `"Link/Currency" in col`, but
based-on and group-by columns are dicts, so the test checked the dict's keys
and never matched. currency_col_idx stayed None and the grand-total row's
currency cell was left unset, so Total(Amt) rendered with the global default
currency instead of the company's.
Match the dict's fieldtype/options instead. Dict columns are never numeric
and string columns are never Link columns, so the two branches are now
mutually exclusive.
a30aac87bf