Close Phase 47 queue

[YSCJRH]

Summary

• Syncs README and tracked queue docs to the Phase 47 closeout state.
• Records that Phase 47: sync repo truth to successor queue #366-Phase 47: main-path product containment #369 are closed through PRs Sync Phase 47 queue state #370-Record Phase 47 main-path containment #373 and that Phase 47 exit gate #365 remains the protected closeout gate until this PR merges.
• Keeps the next successor state paused until a fresh milestone, blocked exit gate, and ready work items are explicitly approved.

Closes #365

Validation

• python scripts/check_no_secrets.py
• python -m backend.app.cli audit-github-queue --repo YSCJRH/mirror-sim
• python -m backend.app.cli classify-lane --files README.md docs/plans/automation-roadmap.md docs/plans/current-state-baseline.md docs/plans/phase-47-successor-gate-2026-05-16.md docs/plans/phase-execution-queue.md
• gh issue list --milestone "Phase 47 - Boundary Readiness and Successor Hygiene" --state all --json number,title,state,labels,url
• git diff --check

Notes

• Docs-only closeout. No public API, frontend route, artifact layout, scenario DSL, claim/evidence, run trace, or Mirror Codex MCP contract changes.
• After this PR merges, close the Phase 47 milestone and rerun audit-github-queue to confirm the no-open-milestone paused state.