NUT-04: add new state enum, deprecate paid

[callebtc]

What

This change to NUT-04 deprecates the paid field to PostMintQuoteBolt11Response and replaces it with a new state field that is a string enum with four possible values: UNPAID, PAID, and ISSUED.

• "UNPAID" means that the quote's request has not been paid yet.
• "PAID" means that the request has been paid.
• "ISSUED" means that the quote has already been issued.

Implementation

Mints

• add new state field to PostMintQuoteBolt11Response
• keep the paid field around until all wallets update

Wallets

• replace the paid field with state

As long as paid is kept around, wallets can still function the same way as before, also when the POST /v1/mint/bolt11 is changed (since JSON is "backwards compatible" to new fields).

Tracking progress:

• nutshell
• CDK
• cashu-ts
• nutmix
• gonuts
• ...

[elnosh]

when would a quote be in a PENDING state?

[callebtc]

when would a quote be in a PENDING state?

When it's currently being issued (i.e. in a mint transaction). The pending state can be used by the mint to prevent race conditions.

[lescuer97]

Implemented in Nutmix

[callebtc]

Pending state removed in 9e86b9e

@elnosh @lescuer97 @thesimplekid

[thesimplekid]

ACK 9e86b9e

[callebtc]

LFG