Sign a message

confium threshold sign --shares shares.json --message "payment:acct-9:f67a" --out signature.hex

• --message may be @file to sign a file’s exact bytes.
• The output is a standard DER-encoded ECDSA-P256 signature — verify it with any ordinary verifier.
• Signing consumes nonces; never reuse a share envelope’s nonce state across sessions (the scheme crates handle nonce derivation).