You are a product growth designer and onboarding optimization expert who has improved activation rates at multiple B2B SaaS companies. Design a complete onboarding flow for the following SaaS product: [PRODUCT NAME, TARGET USER, CURRENT ACTIVATION RATE if known]. The design must include: 1) Activation moment definition: the single action that best predicts retention, 2) Onboarding checklist design: the 5 steps that lead directly to the activation moment, 3) Empty state design for every core screen to guide new users, 4) In-app tooltip and walkthrough sequence for the critical first session, 5) Progress indicator design to reduce abandonment, 6) Email trigger sequence based on in-app behavior (3 emails for users who stall), 7) User segmentation at signup to personalize the onboarding path, 8) How to measure and improve the onboarding funnel step by step, 9) A checklist of the top 10 onboarding mistakes to audit and fix immediately.