Directory authorities should enable ExtendByEd25519ID

This option has been supported since 0.3.0; it is no longer a fingerprinting risk, and should be enabled for everybody.

@tpo/core Any objections, or should I ask dir-auths@ to do this? Do you think we need to do more testing first?

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information