Produce a governance playbook for a dark mode design system in the {{industry}} sector. Write in a {{tone}} tone for {{target_audience}}. The primary goal is {{goal}}. Use a structured playbook format with measurable success criteria. Each play must include action, responsible role, and expected outcome. Use plain language. Organize into: Overview, Prerequisites, Step-by-step Plays (7 plays covering proposals, modifications, QA, release, documentation, adoption, roadmap), Metrics to Track, and Troubleshooting Guide. Maximum 1600 words. Skip any section if unknown. Do not include generic advice. Paste any relevant background information after these instructions before running.