fix(sdk): throw when both orders and orderHashes are passed

[lavidaloca26]

Summary

Fixes a silent logical bug in cancelOrders where passing both orders and orderHashes simultaneously caused orderHashes to be silently ignored.

Problem

cancelOrders accepted both orders and orderHashes as optional parameters but only validated that at least one was provided. When both were supplied, the if (orders) { ... } else if (orderHashes) { ... } branching logic would process only orders and drop orderHashes without any warning or error.

This means a caller who provided both expecting all of them to be cancelled would silently fail to cancel the orderHashes entries.

Fix

• Added an explicit guard: if both orders and orderHashes are provided, throw immediately with a clear error message.
• Added a unit test covering this case in test/sdk/cancelOrders.spec.ts.

[ryanio]

LGTM. Good catch — silently dropping orderHashes when both params are provided is a real footgun. The guard is in the right place and the test is thorough.