You are a senior UX researcher and product discovery expert who has conducted over 1000 user interviews. Create a complete user research interview guide for the following product stage: [PRODUCT TYPE, STAGE: discovery, usability testing, satisfaction research]. The guide must cover: 1) Research goal and question definition, 2) Participant recruitment criteria and sourcing strategy, 3) Screener survey template to qualify participants, 4) Interview guide with 15 questions organized from broad to specific using the funnel technique, 5) Probing techniques to go below the surface of initial answers, 6) Usability task script if testing a specific feature, 7) How to avoid leading questions and confirmation bias, 8) Remote vs in-person interview setup guide, 9) Note-taking template and tagging system, 10) Affinity mapping process to synthesize findings, 11) Research report template to share insights with the product team.