feat(q-dev): add Kiro Executive Dashboard with cross-source analytics

New dashboard "Kiro Executive Dashboard" with 12 panels covering:
- KPIs: WAU, credits efficiency, acceptance rate, steering adoption
- Trends: weekly active users, new vs returning users
- Adoption funnel: Chat→Inline→CodeFix→Review→DocGen→TestGen→Agentic→Steering→Spec
- Cost: credits pace vs projected monthly, idle power users
- Quality: acceptance rate trends, code review findings, test generation
- Efficiency: per-user productivity table with credits/line ratio

Correlates data across user_report (credits), user_data (code metrics),
and chat_log (interaction patterns) for holistic Kiro usage insights.

Author: warren830