Add service-quota-check skill and service-quotas-monitor custom agent

- New skill: service-quota-check — checks AWS service quota utilization,
  flags quotas at 85%+ utilization, requests increases via Service Quotas
  API, and recommends support cases for non-adjustable quotas
- New custom agent: service-quotas-monitor — proactively scans all regions,
  identifies quotas approaching limits, and takes automated action
- Updated CloudFormation template with ServiceQuotaCheck IAM policy
- Updated CLAUDE.md, kiro conventions, llms.txt, and root README