Créer un magic link

{
  "transfer_id": "tr_abc123def456",
  "expires_in_minutes": 30
}

{
  "id": "mlink_uvw123",
  "token": "mlink_x1y2z3...full-secret",
  "warning": "Save this token now - it will not be shown again.",
  "magic_url": "https://files.coffrify.com/ABC123?ml=mlink_x1y2z3...",
  "expires_at": "2026-06-05T15:00:00Z",
  "short_code": "ABC123",
  "transfer_id": "tr_abc123def456",
  "expires_in_minutes": 30
}