tECDSA Secp256r1 (NIST P-256) key resharing and II subnet downtime

Enable pzp6e to sign with ecdsa:secp256r1:key_1

The resharing of the tECDSA secp256r1 master key from subnet pzp6e to uzr34 as described above was successful.

A new proposal has been submitted to enable this key for signing on fiduciary subnet pzp6e, which is already the signing subnet for the existing master keys.