THE FRENCH INVASION OF BRAZIL has come to Naught, a small city along the coast near Belem, where the French stayed in a stylish hotel along the beach. The main thrust of the French attack was driven off in a samba school bus to see the sights and to dine on local delicacies in several of Naught's excellent sea food restaurants. Brazilian tour group operators hope that the stronger Euro will encourage more French tourists to come to Naught, which has traditionally not received the attention that other regions such as Rio de Janeiro and Bahia have had lavished on them.