[H] Drop claude-pr-review/quality-gate branch-protection requirement

[cbeaulieu-gt]

Parent epic: #273 · Spec: docs/superpowers/specs/2026-05-20-codex-pivot.md §9, §11 (#H)

Scope

Final cutover step after all Claude workflows are removed. Remove claude-pr-review/quality-gate (and the shadow variant) from the main-branch ruleset's required-status-check list.

Acceptance

• claude-pr-review/quality-gate no longer listed as required
• claude-pr-review/quality-gate-shadow no longer listed as required
• codex-pr-review/quality-gate (from #B) remains the sole gate
• Ruleset change documented in shadow-mode decision log (#N)

Gating

• MUST wait for #O (synchronize-event verification) — do NOT delete claude-pr-review.yml without #O's answer
• Shadow-mode decision-gate criteria from spec §8 met (≥7 days AND ≥7 PRs binding, kill-criteria not triggered)

🤖 Generated by Claude Code on behalf of @cbeaulieu-gt