fix(PIIOByteArray): advance pos by actual bytes read, not requested size

readDevice() did pos += size instead of pos += ret. The clamping
on the next line (pos = min(pos, data_->size_s())) masked the
issue in practice, but the semantics were wrong. Aligns with
writeDevice() which correctly uses pos += rs.size_s().

libs/main/io_devices/piiobytearray.cpp

@@ -62,8 +62,7 @@ ssize_t PIIOByteArray::readDevice(void * read_to, ssize_t size) {
 	if (ret <= 0) return -1;
 	memcpy(read_to, data_->data(pos), ret);
 	// piCout << "readed" << ret;
-	pos += size;
-	if (pos > data_->size_s()) pos = data_->size_s();
+	pos += ret;
 	return ret;
 }