In the bowl of a food processor fitted with the steel blade, combine the cream cheese, smoked salmon, mayonnaise, shallot, lemon juice, dill, capers, horseradish, 3/4 teaspoon salt, and 1/4 teaspoon pepper. Pulse a few times to incorporate, scrape down the sides of the bowl, then puree the mixture for 15 seconds. Stop, scrape again, and puree until smooth and spreadable, 10 to 15 seconds more. Scoop into a decorative bowl.