Cybertech, not because it's that great of a crew skill or anything, but once you get SCORPIO you are able to learn a tremendous amount about advanced droid technologies which allows you to modify and build droid parts. Droid slicing is already an agent ability, and with cybertech you deepen your knowledge about droids and their capabilities.
To go along with this, slicing would be a good skill. slicing doesn't provide you with materials for cybertech crafting, but from an agent character perspective, I think it's a good fit. you're hacking into secure systems and gaining information, which seems like what agents are all about