[codex] Fix background review skill read-before-write

[doncazper]

Summary

• Require background review prompts to call skill_view(name='<umbrella>') and read the full SKILL.md before adding support files.
• Keep the review whitelist unchanged while rendering the exact allowed tool names (memory when enabled, skills_list, skill_view, skill_manage) in prompt/error language.
• Extend the background-review read-before-write guard so new support-file writes require the umbrella SKILL.md to be loaded first, and make guard errors agent-actionable.

Fixes #58475.

Tests

• scripts/run_tests.sh tests/run_agent/test_review_prompt_class_first.py tests/run_agent/test_background_review_toolset_restriction.py tests/tools/test_skill_manager_tool.py tests/tools/test_skill_improvements.py -q

Note: the first wrapper attempt found no pytest in the shared fallback venv, so I created a checkout-local .venv with uv sync --extra dev --locked and reran the same command successfully.

[doncazper]

Closing as superseded by #75020. That PR explicitly carries this implementation forward, preserves doncazper as the original author, adds the exact corrective skill_view(...) coverage/messages, and has green checks. Keeping both open would leave maintainers with duplicate copies of the same fix.