Regression from the contract-lock feature: the check gated on any non-empty
ContractLockPurchase, but the blueprint data uses the string "None" (not "")
for items with no lock (749/773 items). So virtually every item returned
'Item is locked' before the currency deduction -> players couldn't buy anything
(error shown, K-Marks unchanged). Skip the gate when the value is null/empty/"None".
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>