chore: expand AGENTS.md on test strategy mental model

[PeterSchafer]

Pull Request Submission Checklist

• Follows CONTRIBUTING guidelines
• Commit messages
  are release-note ready, emphasizing
  what was changed, not how.
• Includes detailed description of changes
• Contains risk assessment (Low | Medium | High)
• Highlights breaking API changes (if applicable)
• Links to automated tests covering new functionality
• Includes manual testing instructions (if necessary)
• Updates relevant GitBook documentation (PR link: ___)
• Includes product update to be announced in the next stable release notes

What does this PR do?

This PR adds important aspects around test strategy and mental model to the Agents.md

Where should the reviewer start?

How should this be manually tested?

What's the product update that needs to be communicated to CLI users?

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues
✅	Code Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.

[github-actions]

	Warnings
⚠️	Since the CLI is unifying on a standard and improved tooling, we're starting to migrate old-style imports and exports to ES6 ones. A file you've modified is using either module.exports or require(). If you can, please update them to ES6 import syntax and export syntax. Files found: AGENTS.md

Generated by 🚫 dangerJS against e5a7144

[snyk-pr-review-bot]

PR Reviewer Guide 🔍

🧪 No relevant tests

🔒 No security concerns identified

⚡ No major issues detected

📚 Repository Context Analyzed This review considered 8 relevant code sections from 4 files (average relevance: 0.83) CLAUDE.md (3 segments, lines 1-116) CONTRIBUTING.md (3 segments, lines 231-407) help/README.md (lines 1-19) dangerfile.js (lines 1-111)

🤖 Repository instructions applied (from AGENTS.md)