feat: enforce device-bound connect challenge

src/gateway/protocol/schema/frames.ts

@@ -46,6 +46,7 @@ export const ConnectParamsSchema = Type.Object(
           publicKey: NonEmptyString,
           signature: NonEmptyString,
           signedAt: Type.Integer({ minimum: 0 }),
+          nonce: Type.Optional(NonEmptyString),
         },
         { additionalProperties: false },
       ),