Fix the money formatter for global orders

An AI wrote a TypeScript helper that formats order totals. It printed a dollar sign and two decimals for every order: fine on the US test account, wrong for everyone else. Your team is replacing it with a formatter driven by the currency and the locale. In production that is Intl.NumberFormat. This version writes the ISO currency code in place of a symbol, so the output stays plain ASCII.

An assistant wrote format_money(amount_minor, currency, locale). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• amount_minor: the amount in the currency's smallest unit, like cents. It can be negative.
• currency: an ISO 4217 currency code, like "USD", in any case. It can be empty.
• locale: a locale tag, like "en-US".
• Return the formatted amount as a string.

Rules the tests check:

• Uppercase the currency code.
• The currency's minor units are the digits after the decimal separator. They are 0 for JPY, KRW, VND, CLP and ISK, and 3 for KWD, BHD, JOD, OMR and TND. Every other code has 2, including an empty or unknown one.
• The locale, matched exactly, sets the separators and where the code goes:
  • de-DE, es-ES and it-IT: group with ., decimal ,, code after the number.
  • fr-FR: group with a space, decimal ,, code after the number.
  • Any other locale, including "": group with ,, decimal ., code before the number.
• Split the absolute amount into a whole part and its last minor-unit digits. Pad with leading zeros so the whole part has at least one digit: 5 cents is 0.05. With 0 minor units there is no decimal separator.
• Group the whole part in threes from the right.
• Join the code and the number with one space. With an empty code, return the number alone.
• A negative amount gets one - in front of the whole result, code included.