docs(codex): reconcile campaign milestone status

[SUaDtL]

Summary

• Record M0 through M3 as accepted from the merged Codex implementation and live 0.144.1 evidence.
• Keep M4 agent packaging pending and M5 distribution partial instead of falsely closing codex.feature.0001.
• Preserve the H-18 protected-file blocker for the stale beta sentence in CONTEXT.md; no override was taken.

Why

The campaign task looked stale because stable ca-codex 0.2.4 was already tagged, published, and documented. The authoritative parity ledger still leaves packaged agents and the remaining worker-backend distribution unfinished. This change makes that boundary explicit in the approved campaign plan.

Verification

• All canonical scripts from .codearbiter/tech-stack.md passed.
• python -m unittest discover -s plugins/ca/hooks/tests -p test_*.py passed: 967 tests.
• python .github/scripts/check-plugin-refs.py passed.
• Fresh evidence check matched the stable ca-codex-v0.2.4 manifest and release to the M0 through M5 status table.
• Manual and _hooklib.SECRET_RE scans found zero secrets.
• git diff --check passed.

Review

Coverage audit: PASS. This is documentation and append-only sprint evidence only, with no behavioral source or TDD obligation.

Conflict hierarchy level 1 applies: preserve H-18 and the activation-switch audit boundary instead of bypassing it for a status correction.

Ref: ADR-0011

[SUaDtL]

Superseded by #313, the single hackathon review surface. This PR's recorded head and changes are represented in #313's exact 16-PR / 29-commit / 126-path source manifest. PR #313 passed final exact-head CI at commit 6173b1d and remains open and unmerged. Closing this source PR to avoid parallel review; please continue review and discussion on #313.