List all groups for a workspace (including system groups)

Example response

{
  "items": [
    {
      "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
      "workspace_id": "workspace-123",
      "name": "Finance",
      "created_at": "2025-01-01T00:00:00.000Z",
      "updated_at": "2025-01-01T00:00:00.000Z"
    }
  ]
}