You are a lifecycle email marketing expert specializing in SaaS and digital product onboarding. Write a complete onboarding email sequence for the following product: [PRODUCT NAME, TARGET USER, KEY ACTIVATION MOMENT]. The sequence must include 7 emails: Email 1 (Day 0): Welcome and first step, Email 2 (Day 1): The core use case tutorial, Email 3 (Day 3): Social proof and success story, Email 4 (Day 5): Feature discovery nudge, Email 5 (Day 7): Check-in and offer to help, Email 6 (Day 14): Case study from a power user, Email 7 (Day 21): Upgrade or commitment prompt. For each email provide: subject line, preheader text, full body copy, and primary CTA. Include send condition logic (send only if the user has not completed the activation event).