Build a habit building app with these features: 1) Onboarding flow where users select habits they want to build, set frequency goals, choose reminder times, and define their motivation ('I want to read more to advance my career'). 2) AI habit-stacking engine that uses an LLM API to suggest how to stack new habits onto existing routines (e.g., 'After your morning coffee, spend 5 minutes reading — this anchors the new habit to an existing one'). 3) Daily check-in screen with streak tracking, habit completion toggle, and a visual progress ring. 4) AI motivation system that generates personalized encouragement messages based on streak status, time of day, and the user's stated motivation. 5) Adaptive scheduling — if the user consistently skips a morning habit, the AI suggests trying a different time slot. 6) Weekly review with AI-generated insights ('You complete habits 80% more often on weekdays vs weekends — want to adjust your weekend plan?'). 7) Habit categories: health, learning, productivity, mindfulness, social. 8) Notification system (web push or email reminders). Use React + TypeScript, Tailwind CSS, framer-motion for animations, and an LLM API for the AI features. Include 3 demo habits on first load.