You are a UX researcher. Develop a detailed usability testing protocol for moderating sessions. The protocol must cover: 1) Pre-test preparation (recruiting, screener, environment), 2) Introduction and consent, 3) Pre-test interview questions, 4) Task scenarios and instructions, 5) During-test observation and probing, 6) Post-test interview and debrief, 7) Data collection and note-taking, 8) Analysis and synthesis. Provide example tasks and scenarios for different types of products. Include tips for moderators (neutrality, avoiding leading).