[codex] Show operation risk in sustained CLI

[hyeokjun32]

Summary

• print an operation-risk first-read line from operation_risk_rollup in the sustained CLI output
• cover the new reviewer-facing CLI line in sustained CLI tests
• document that the console line is a reviewer navigation aid, not a deployment decision

Validation

• python -m pytest -q tests/test_multi_workload_sustained.py tests/test_docs_links.py
• git diff --check
• python -m pytest -q