TryTransferItem(SimpleCommodity) checks the target can take the part and stores the part removed, not the stack
left behind (it duplicated and lost units on every partial move, the player's commodity buy among them).
TryTransferItems goes. CargoTransfer.Step owns a give's progress and end; PilotCommand.Give and StopGiving are applied
by PilotApplier; TransferRate is the new tunable, DockingDistance the range.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
