Generate tentative research questions from profiled dataset outputs. Takes profile.json and variable_types.json (produced by /load-and-profile) and produces research_questions.json with a primary PICO/PECO question, secondary questions, feasibility assessment, and variable role assignments. Use this skill whenever the user wants to formulate research questions, generate hypotheses, or move from data profiling to study design. Triggers on: "generate research questions", "formulate hypotheses", "what questions can we answer", "research question", "PICO", "study question", or any request to go from profile.json to research_questions.json.