TESTNET_POSITION_LOT_SIZE top-level property
Testnet's position_lot_size, read from the deployment record. Validation
uses the lot size of the config actually in play; this is the convenience
constant for testnet callers.
(The official SDK exports this as POSITION_LOT_SIZE from the package
root; Dart renames it so it cannot shadow the Move constant
cost.POSITION_LOT_SIZE in a flat export.)
Implementation
final BigInt TESTNET_POSITION_LOT_SIZE =
BigInt.from(testnetPredict.units.positionLotSize);