In a large nonstick wok or skillet, heat 1 tablespoon oil until shimmering. Add the shrimp, scallops and squid and cook over high heat, stirring occasionally, until browned and cooked through, 2 to 3 minutes. Transfer the seafood to a plate. Heat the remaining 1 tablespoon of oil. Add the shallots, garlic and carrots and cook over high heat, stirring occasionally, until lightly browned, about 5 minutes. Add the noodles and scallions and stir-fry until heated through, about 2 minutes.