Build an AI skincare routine generator with the following numbered features: 1. An onboarding quiz covering skin type, main concerns, sensitivity, climate, budget, and time available per day. 2. Generation of morning and evening routines in order: cleanser, treatment, moisturizer, SPF, with plain-language reasons for each step. 3. An ingredient conflict checker that flags combinations such as retinol plus strong acids and explains safe timing alternatives. 4. A product matcher that maps each step to drugstore and premium options at the user's budget, with affiliate-ready links. 5. A my shelf feature where users add products they already own and get a routine built only from those. 6. Progress tracking with weekly check-ins and photo-free self-reports on breakouts, dryness, and irritation. 7. A patch test and pregnancy-safe mode that filters out contraindicated ingredients. 8. A routine explainer page that teaches the why behind each active ingredient in simple terms. 9. A clear non-medical disclaimer and a referral card to a dermatologist for persistent concerns. 10. Seasonal routine adjustments that shift hydration and SPF emphasis based on the user's weather.