[codex] Add Codex project environment

[jamestjsp]

Summary

• Add project-scoped Codex config for workspace-write, on-request approvals, and workspace network access.
• Add a shared Codex local environment for ctrlsys with setup, cleanup, and common actions.

Validation

• Parsed .codex/config.toml and .codex/environments/environment.toml with Python tomllib.

Notes

• Did not run the Python test suite; this change only adds Codex project environment metadata.