message: fix: use correct buffer size for hashmode in stacking
diff: @@ -325,7 +325,7 @@ export class StackingClient {
  return Promise.all([balancePromise, poxInfoPromise])
  .then(([balance, poxInfo]) => {
  const { hashMode, data } = decodeBtcAddress(poxAddress);
  - const hashModeBuffer = bufferCV(toBuffer(BigInt(hashMode)));
  + const hashModeBuffer = bufferCV(toBuffer(BigInt(hashMode), 1));
  const hashbytes = bufferCV(data);
  const poxAddressCV = tupleCV({
  hashbytes,
  