Update conversation assignment

{
  "data": {
    "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
    "user_id": "f1e2d3c4-b5a6-9870-fedc-ba0987654321",
    "created_by_user_id": "f1e2d3c4-b5a6-9870-fedc-ba0987654321",
    "notes": "Customer issue resolved",
    "active": true,
    "created_at": "2026-01-19T10:30:00Z"
  }
}

{
  "error": "<string>"
}

{
  "error": "<string>"
}

{
  "error": "User not found or not a member of this project"
}