Expose reasoning effort level in statusline JSON input

Feature Request

The statusline script (~/.claude/statusline.sh) receives a JSON payload with model info, context window, session ID, output style, etc. — but reasoning effort level (low/medium/high) is not included.

Use Case

I'd like to display the current effort level in my statusline so I can see at a glance what mode I'm operating in, e.g.:

λ Claude Opus 4.6 | Taper | 12% | explanatory | abc123 | effort: high

Current Behavior

There is no .effort, .reasoning_effort, or similar field in the statusline input JSON. The effort level is a configurable setting but isn't exposed to the statusline script.

Requested Behavior

Add a field to the statusline JSON input, e.g.:

{
  "reasoning_effort": "high"
}

Values would be "low", "medium", or "high" matching the current effort level options.