[Feature Request] Add token direction field to subagent status line JSON

Bug Description
the subagent status line JSON contains no info about the subagent's "token direction", i.e. it is not possible to display the original "upward or downward facing arrow" in a custom subagent status line

Environment Info

• Platform: linux
• Terminal: konsole
• Version: 2.1.238
• Feedback ID: 919b2de8-6ccb-405a-8f6a-9af6d339fa75

Output as of 2.1.238:

{
  "session_id": "...",
  "transcript_path": "...",
  "cwd": "...",
  "prompt_id": "...",
  "columns": 169,
  "tasks": [
    {
      "id": "a9694f99227974bfe",
      "type": "local_agent",
      "status": "running",
      "description": "haiku (low) - Infinite block test 1",
      "label": "Backgrounding infinite bash processes",
      "startTime": 1787309508060,
      "model": "claude-haiku-4-5-20251001",
      "contextWindowSize": 200000,
      "tokenCount": 21626,
      "tokenSamples": [
        ...
      ],
      "cwd": "...."
    },
[...]
    {
      "id": "aeee17882615c47fe",
      "type": "local_agent",
      "status": "running",
      "description": "haiku (low) - Infinite block test (nested)",
      "label": "Reinvoking timeout sleep loop",
      "startTime": 1787309763895,
      "model": "claude-haiku-4-5-20251001",
      "contextWindowSize": 200000,
      "tokenCount": 19584,
      "tokenSamples": [
        ...
      ],
      "cwd": "..."
    },
  [...]
  ]
}

Original looks like this:

<img width="1133" height="120" alt="Image" src="https://github.com/user-attachments/assets/a7430201-8894-4b65-aaa4-cc502e81044b" />