WASHINGTON — The lead investor in a South Korean aluminum company that has challenged Commerce Department penalties on certain exports from South Korea to the United States made a $2 million payment last year to President Trump’s holding company.The payment by the parent company, Base Group, was revealed for the first time in Trump’s annual financial disclosure form released in late June.The document offered only a cryptic explanation for the payment, stating that it was part of a “letter of intent” and a “nonrefundable development fee.” In statements to The New York Times, the company and the Trump family said…