Add effort level to statusLine JSON data

Feature request

The statusLine command receives JSON with model info, context window, cost, workspace, etc. — but effort level is missing.

Since effort level (high, medium, low) directly affects model behavior and token usage, it would be useful to display it in the status line alongside the model name and context remaining.

Proposed change

Add an effort field to the statusLine JSON input, e.g.:

{
  "effort": {
    "level": "high"
  }
}

Use case

I customize my statusLine to show key session info at a glance. Effort level is one of the few settings that significantly changes how the model operates, but there's no way to surface it in the status line today. Having it available would help users stay aware of their current effort setting without needing to check /config.