Flight menu combinations

A tasting counter builds a flight from its printed menu, where dish_names[i] is a dish and stations[i] is the kitchen station that cooks it. A flight takes exactly flight_size dishes, keeps them in menu order, and never uses the same station twice, because one station cannot plate two courses in the same service. Return every possible flight as a string: the chosen dish names joined by a plus sign padded with single spaces, so two dishes read as "miso egg + yuzu tart". List the flights in the order a left to right scan of the menu finds them, so a flight whose first dish sits earlier on the menu comes first, and ties break on the next dish chosen. Return an empty list when no flight fits. The menu holds at most 8 dishes and flight_size is at least 1.