Skillet Fideuà with Shellfish and Garlic Aioli

Name: Skillet Fideuà with Shellfish and Garlic Aioli
Ingredients: 12 ounces tomatoes (about 2 medium tomatoes); 1 small yellow onion (about 6 ounces); 2 tablespoons safflower oil; 6 ounces peeled and deveined raw large shrimp; 6 tablespoons extra-virgin olive oil, divided; 10 1/2 ounces uncooked medium fideo pasta (such as El Mexicano Fideo Mediano); 8 garlic cloves, finely minced (about 1/3 cup); 1/2 teaspoon kosher salt, plus more to taste; 3/4 teaspoon sweet mild pimenton; 2 cups seafood stock; 8 clams, scrubbed; 8 mussels, scrubbed and debearded; Garlic Aioli; Lemon wedges, for serving