Function signNonce

signNonce(seed: string, nonce: Uint8Array): Promise<SignedNonce>
Signs a NATS server nonce with the ed25519 key carried by a seed string.

Decodes the seed, derives the public nkey string for its role, and produces a detached ed25519 signature over the raw nonce bytes encoded as base64url without padding. This is the exact pair the NATS CONNECT message expects in its nkey and sig fields.
Parameters
- seed: string
  The base32 seed string, e.g. SUAB....
- nonce: Uint8Array
  The raw nonce bytes from the server INFO message.
Returns Promise<SignedNonce>
The public nkey string and the base64url signature.
Throws
If the seed is malformed or cannot be imported.

Since
1.0.0
Example
```
import { signNonce } from 'edgeport/nats';
const nonce = new TextEncoder().encode('server-nonce');
const { nkey, sig } = await signNonce('SUAEL6GG2L2HIF7DUGZJGMRUFKXELGGYFMHF76UO2AYBG3K4YLWR3FKC2Q', nonce);
```
- Defined in src/nats/nkey.ts:234