Expand cloud requirements to cover managed config fields

[viyatb-oai]

Summary

• Extend cloud requirements parsing to accept the same requirements.toml fields supported by managed configuration, including MCP server requirements, app requirements, exec-policy rules, residency, guardian policy config, and network constraints.
• Surface those fields through configRequirements/read and update the app-server protocol schemas and generated TypeScript types.
• Add regressions proving cloud-loaded network requirements flow into effective config loading.

Testing

• cargo test -p codex-cloud-requirements fetch_cloud_requirements_parses
• cargo test -p codex-core load_config_layers_includes_cloud_network_requirements
• cargo test -p codex-app-server-protocol
• just fix -p codex-core
• just fmt