chore: Adds CLAUDE.md and AGENTS.md

[kailash-b]

✏️ Changes

This PR introduces a consolidated AI agent instruction set for the repository, centered on a new CLAUDE.md with supporting references/ files, and slims AGENTS.md down to a pointer so all agents share one source of truth.

Added

• CLAUDE.md — primary AI agent guidelines: role, working principles, project overview/structure, key files, boundaries (Always Do / Ask First / Never Do), security considerations, and one-line anchors linking to the reference docs.
• references/code-style.md — naming detail, good/bad examples, and dominant patterns (fluent builder, options, event-handler wrapping).
• references/commands.md — full build/test/coverage/docs command list.
• references/docs-update.md — tracked-docs inventory and code-to-docs mapping.
• references/git-workflow.md — branch naming, commit style, CHANGELOG format.
• references/pitfalls.md — common gotchas (Domain without https://, DPoP mode semantics, event preservation, InternalsVisibleTo, multi-targeting).
• references/testing.md — testing conventions, mocking, integration-test helpers, and live-test command.

Modified

• AGENTS.md — reduced from the previous full instruction copy to a short stub that points at @CLAUDE.md, so non-Claude agents (Codex CLI, Gemini CLI, etc.) read the same guidelines. Eliminates duplication and drift between the two files.

🔗 References

🎯 Testing

• This change adds unit test coverage
• This change adds integration test coverage
• This change has been tested on the latest version of the platform/language or why not — N/A, documentation-only change with no runtime impact.

✅ Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All existing and new tests complete without errors
• All commits are signed.