Switching between single keypair and unique keys per credential

[pstamatop]

Is it possible to make the wallet configurable, allowing a switch between using a single public-private key pair for all credentials versus unique keys per credential?

This could be useful in scenarios where combined presentations of credentials (e.g. an EHIC without personal information alongside a PID) require binding to a single proof for verification, since claim-based binding isn't possible. This switch could act as a practical temporary solution until full unlinkability is achieved.

@emlun would love to hear your thoughts on this - also tagging @kkmanos and @gkatrakazas to keep both in the loop