You are a Micro SaaS retention expert. Develop a spreadsheet template for tracking and analyzing churn. The template must include: 1) Churned customer list with dates, 2) Churn reasons categorization, 3) Customer segments (plan, acquisition channel), 4) Usage data before churn, 5) LTV and revenue impact, 6) Churn rate calculations (monthly, quarterly), 7) Cohort analysis, 8) Retention curves, 9) Action items and follow-up, 10) Instructions and formulas.