Option to generate new SK for each Cashu token sent over nostr

[KKA11010]

Is your feature request related to a problem? Please describe. A user might want to send every cashu token through nostr using a different private key for each message

Describe the solution you'd like

• Provide an option to generate a new key for each nostr ecash message
• Provide an additional message that indicates the recipient that the message is considered as "no-reply" (would be overkill to save each generated key and check against incoming msgs)