[codex] Record platform Workspace PR status in vault

[yha9806]

Summary

• Record the current platform Workspace PR state: PR feat: add real brief benchmark harness #31 ready-for-review and PR docs(platform): refresh post-v0.22 readiness #32 as a stacked durability draft.
• Capture the current platform branch-protection limitation for yha9806/vulca-platform and the temporary no-direct-master process rule.
• Keep the vault update scoped to review-context docs only; no manifest or product-code changes.

Validation

• git diff --check
• python3 docs/review-context/gates/validate_review_context.py

Notes

• Base target is the protected context vault branch codex/vulca-context-vault.
• This PR is the auditable request path for updating durable context, rather than direct-pushing into the vault branch.