Write a complete YouTube video script in a {{tone}} tone for {{target_audience}} about {{topic}} to achieve {{goal}}. Include: pre-production notes, a 30-second hook, introduction with subscribe CTA, 4-6 main content segments with on-screen titles and engagement cues, a climax with a key insight, conclusion with CTA, and YouTube optimization (5 titles, description template, 15 tags, thumbnail concept, card timestamps). Keep script 2000-3000 words for a 15-20 minute video. Use plain language. Paste any relevant background information after these instructions before running.