curl --request GET \
  --url http://localhost:8080/api/metrics \
  --header 'Authorization: Bearer <token>'

{
  "cpu": {
    "percent": 123,
    "load_avg_1min": 123
  },
  "memory": {
    "total_bytes": 123,
    "used_bytes": 123,
    "available_bytes": 123,
    "percent": 123
  },
  "disk": {
    "total_bytes": 123,
    "used_bytes": 123,
    "available_bytes": 123,
    "percent": 123
  },
  "worktrees": [
    {
      "path": "<string>",
      "session_id": "<string>",
      "size_bytes": 123
    }
  ],
  "active_sessions": [
    {
      "session_id": "<string>",
      "task_id": "<string>",
      "task_title": "<string>",
      "started_at": "<string>",
      "duration_seconds": 123
    }
  ],
  "session_count": 123,
  "system": {
    "uptime_seconds": 123,
    "python_version": "<string>",
    "server_start_time": "<string>"
  }
}