feat(q-dev): add Kiro Credits + DORA Correlation dashboard (#8792)

Add a new Grafana dashboard that correlates Kiro AI usage (credits,
messages, active users) with DORA metrics at weekly aggregate level.

Panels include:
- Pearson's r correlation between weekly credits and PR cycle time
- High AI Usage vs Low AI Usage cycle time comparison
- Weekly credits vs deployment frequency trend
- Weekly credits vs change failure rate trend

Data is joined by week_start between _tool_q_dev_user_report and
project_pr_metrics / cicd_deployment_commits.

Author: warren830