Evaluation of the Positive Peers Mobile App for Supporting the Viral Suppression of Young People With HIV: Protocol for a Concurrent Mixed Methods Evaluation With Randomized Controlled Clinical Trial and Observational Cohort. - Step MM; Catania LA; McMillen Smith J; Lewis SA; Bitar Y; Cheruvu VK; Berg KA; Hallam JS; Avery AK (JMIR research protocols, 2026)