Uninitialized `maturityDate` in `Strategy.create()`

The Strategy.create() function declares a maturityDate return value but never initializes or sets it. This uninitialized value, which defaults to 0, is returned and passed through to OperationalTreasury._buy(), where it's emitted via the LiquidityLocked event.

This leads to misleading or incorrect event logs, particularly showing maturityDate = 0.

The uninitialized value flows through to event emission:

function _buy(...) internal {
    // ...
    (sizeUSD, premium, maturityDate) = strategy.create(...);
    // maturityDate passed unchanged -> maturityDate: 0
    _emitEvent(optionID, amount, sizeUSD, buyToken, premium, fees, maturityDate);
}

Ensure that Strategy.create() explicitly sets and returns a maturityDate.