MALÉ, Maldives—The white sand beaches, turquoise waters and secluded luxury resorts of this South Asian archipelago attract millions of tourists each year. But a new trade has quietly emerged behind the postcard-perfect backdrop: a web of companies helping Russia evade sanctions. Hundreds of millions of dollars in goods that are restricted or destined for sanctioned companies have changed hands at the airport, according to documents reviewed by The Wall Street Journal and interviews with Western officials. Some of these goods serve both civilian and military uses. The airport’s cargo holds are often filled with aircraft parts and electronic components, as…