Allow [otel] configuration to be set via cloud-managed defaults in admin console

What variant of Codex are you using?

App, CLI

What feature would you like to see?

The [otel] block in managed_config.toml already supports pushing observability configuration (exporter
endpoint, headers, environment, log_user_prompt) as managed defaults. However, the admin console only
exposes requirements (approval policies, sandbox modes, MCP servers, command rules) & there is no way to
push [otel] configuration from the console.

### Problem

We want to centrally roll out telemetry to an OTLP collector. Currently the only options are:

• Deploy /etc/codex/managed_config.toml to every machine via MDM or a config management tool
• Ask users to self-configure ~/.codex/config.toml

Neither is viable for teams without MDM who need a centrally-managed rollout without relying on per-user
setup.

### Request
Expose the [otel] table fields as managed defaults in the admin console policies UI - the same surface
already used for requirements:

• environment
• exporter (with endpoint and headers sub-fields)
• trace_exporter (with endpoint and headers sub-fields)
• log_user_prompt

Is this planned? If not, what's the recommended path for enterprise teams without MDM to roll out otel
fleet-wide today?

Additional information

_No response_