[Andreas-Garcia]

Summary

Make the standards repository's agent guidance available to Claude and Codex from shared sources, and offer Python consumers an optional portable guidance bootstrap with a pinned drift check.

Existing consumer guidance files are preserved. The opt-in defaults to false; projects with existing files must reconcile them with the agent-config contract before enabling the check.

Type of change

Feature: shared guidance and optional Copier template files.

Test plan

• Rendered Copier templates with the option off and on; checked the generated project and workflow.
• Verified existing agent files and workflow survive an overwrite-enabled Copier copy.
• Ran the documented pre-commit hooks on a rendered template; all applicable hooks passed.
• Ran actionlint, ShellCheck, and the public engine's project adapter and generation checks.
• GitHub CI and independent review remain pending.

Checklist

• Updated documentation, migration guidance, and changelog.
• Pinned the reusable workflow and public engine.
• Existing consumer files are protected.