Feature Request - POS - PIN for Boltcard payments

[arbadacarbaYK]

LUD21* update is about an optional PIN before (BoltCard) withdrawals / payments above a certain amount are allowed.
4 digits pin, 3 retries before link/card invalidation seems consensus.
Static LNURLw requests are not in focus for this, only Boltcard requests.

*lnurl/luds#200
A subset of potentially deriving errormessages are mentioned there, too.

Its already implemented here for reference https://github.com/boltcard/bolt-card-pos

Issuers of Boltcards/Boltcardhubs are : BTCpay, LNbits, Bolt Card Wallet + private Boltcardhubs
PIN is optional, configurable when setting up the card. Feature should not be based upon UID because random-UID is planned.
Issuer invalidates (deactivates) card on 3 failed PIN-retries

[kingonly]

This is still an open proposal, right? We'll consider implementing once merged