Improve review summaries and add live GTM verification

[jtrackingai]

Summary

This PR improves the review experience for audit, upkeep, page grouping, and schema generation.

It also adds an optional verify-live-gtm flow to validate published GTM tracking by simulating browser behavior and capturing real GA4 requests.

Version is bumped to 1.0.6.

What changed

• Added decision-ready summary rendering for:
  • audit
  • upkeep
  • page group
  • event schema / tracking plan
• Updated closeouts to use:
  • summary first
  • files last
• Added verify-live-gtm plus new live verification artifacts:
  • live-preview-result.json
  • live-preview-report.md
  • live-tracking-health.json
• Updated run-health-audit and run-upkeep to optionally run live GTM verification
• Refocused README.md and docs/skills.md on user-facing skill usage
• Strengthened schema-generation guidance so the schema agent behaves more like an event tracking design expert

Why

• Make audit/upkeep outputs easier to review and act on
• Provide real verification for published live GTM quality
• Improve schema quality and consistency

Validation

• Relevant automated tests passed