[codex] Add TKO 4.0 release plan

[brianmhunt]

Summary

Add a dedicated TKO 4.0 release plan under plans/.

This plan turns the release discussion into a concrete operator checklist covering:

• release scope and versioning decisions
• docs timing for a stable launch
• technical preflight and publish checks
• trusted publishing / provenance rehearsal
• final release-day and post-release verification

Why

Issue #271 is being used to solicit feedback on gaps to a proper 4.0 release. This PR captures the current release checklist in one place so we can review, tighten, and execute it deliberately.

Validation

• Reviewed existing plans/ format and matched the same style
• Cross-checked the plan against current Changesets and release workflow configuration
• No runtime or package code changed

Refs #271

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 36eeeea0-aade-4bad-b387-38e8f8107af7

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/tko-4-release-plan

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[brianmhunt]

Closing this as stale now that trusted publishing has landed, the provenance rehearsal succeeded, and the active 4.0 release payload is in #274. Keeping #271 as the discussion thread and #274 as the operational release PR.