nostr:nprofile1qqsw3znfr6vdnxrujezjrhlkqqjlvpcqx79ys7gcph9mkjjsy7zsgygpr9mhxue69uhhqatjv9mxjerp9ehx7um5wghxcctwvsq3samnwvaz7tmjv4kxz7fwdehhxarjd93kztnrdaksz9thwden5te0wfjkccte9ekk7um5wgh8qatz7tvu4p Why is Shamir sharding not doable on coldcards?