Publish provider-owned standalone Codex support

[rudijetson]

Summary

Publish the already-completed CLI ownership migration that treats Codex as an OpenAI/provider-owned standalone installation while retaining RUDI integration, instructions, skills, and Agent Host launch support.

Invariants

• Never accept a RUDI-owned executable as the external Codex provider binary.
• Never remove a legacy installation before a standalone absolute-path version probe succeeds.
• Preserve Codex auth, configuration, sessions, plugins, and skills.
• RUDI may detect, integrate, and launch Codex but must not own its executable or updates.
• Keep the primary follower checkout untouched; verify from the clean dedicated worktree.

Coordinated source

The matching Registry change is the remote codex/codex-standalone-ownership branch in learnrudi/registry.

Acceptance criteria

• Full CLI tests pass on current origin/main plus the one ownership commit.
• Build reproducibility, package dry run, and changed-file debt scan pass.
• Generated manifests encode the provider-owned system contract.
• Open a focused PR linked to the Registry issue/PR.
• Do not perform any host installation or migration as part of this follower submission.

[rudijetson]

Published as PR #14 from the clean dedicated worktree. Local acceptance: 647 tests; reproducible build; 0 debt findings; package dry run; and diff check all passed. GitHub quality CI is queued. Coordinated Registry PR: learnrudi/registry#24.