Go envelope v1.154 — Janus UI reference alignment

UI/UX reference alignment for the Janus envelope.\n\n- Align sidebar/logo, artwork scaling, and nav icon centering with the sophisticated Janus reference.\n- Rework Access into a governance workbench with role lanes, duties, route gates, readiness, and status posture.\n- Add data-backed route gate state and verification coverage.\n\nVerification before release:\n- go test ./...\n- git diff --check\n- Playwright route sweep: 8 routes x desktop/mobile, zero layout issues.