fix: remove redundant makerOrders.length > 0 check in _matchOrders()

[dev-khimesh]

Description

The external matchOrders() already validates makerLength > 0 before calling _matchOrders(). Since _matchOrders is an internal function with a single caller (matchOrders), the duplicate require(makerOrders.length > 0, NoMakerOrders()) inside _matchOrders can never fail independently of the first check.

Gas Savings

• Per call savings: ~20 gas (MLOAD + ISZERO + JUMPI)
• Total historical TXs: ~129M matchOrders calls
• Total potential savings: ~2.58B gas across all historical transactions

Change

Removed the redundant require(makerOrders.length > 0, NoMakerOrders()) from _matchOrders() in Trading.sol. The external matchOrders() entrypoint in CTFExchange.sol already enforces this invariant.

Closes #101

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Note

Low Risk
Behavior is unchanged for callers; the invariant is still enforced on the sole external entrypoint with no new code paths.

Overview
Removes the duplicate require(makerOrders.length > 0, NoMakerOrders()) at the start of internal _matchOrders() in Trading.sol.

matchOrders() in CTFExchange.sol already requires makerLength > 0 before it calls _matchOrders, and that internal function has no other callers, so the inner check could never fail on its own. Empty-maker protection is unchanged at the public entrypoint; this only drops redundant runtime work on every match (~20 gas per matchOrders call).

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