docs(enneagram): add PR train retrospective

[fermatmind]

What changed

• Added a retrospective documentation package for the Enneagram content-asset PR train.
• Included an overview, PR ledger, architecture/ops lessons, and an index README.

Why

The Enneagram content-asset rollout spanned EN13, 90 new pages, 116-page production revalidation, Search Queue/IndexNow, llms.txt, llms-full.txt, and workflow repairs. These docs preserve the operational decisions, PR sequence, and follow-up lessons.

Validation

• python3 markdown sanity checks for all new retrospective files
• git diff --check
• Path-limited staging limited to docs/seo/personality/enneagram/retrospective/**

Deferred items

• No code changes.
• No CMS writes.
• No deployment.
• No Search Queue, IndexNow, llms eligibility, or cache operations.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Don't mint follow-up train IDs outside the manifest

This entry starts a list of concrete future PR-train IDs, but a repo-wide rg shows these IDs exist only in this new retrospective and are absent from docs/codex/pr-train.yaml and docs/codex/pr-train-state.json. The repository AGENTS.md manifest discipline requires proposed future PRs that are not already in the manifest to include title, scope/files, local checks, dependency assumptions, exact manifest/state entries, and an authorization follow-up; otherwise these look like authoritative train items that cannot be executed under the train rules.

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