WsAuthKeyRequest
StockSharp.Ws
Client → server auth via API key. Used by programmatic clients (bots, SDKs) instead of the password flow. The Signature is HMAC-SHA256 over "${KeyId}\n${Timestamp}\n${Nonce}\n" with the API key secret — exchanges' standard wire shape. Reject if outside ±2 min skew or if (KeyId, Nonce) was seen recently (replay).