You are a Micro SaaS growth expert. Create a complete referral program design. The design must include: 1) Referral incentive structure (two-sided rewards), 2) Referral mechanics (how users share), 3) In-app prompts and timing, 4) Landing page for referred users, 5) Email sequence for referrers and referees, 6) Tracking and attribution, 7) Fraud prevention, 8) A/B testing plan, 9) Launch and promotion, 10) Metrics and optimization.