I like the sponsored magic approach. I also like the idea that she doesn't so much grant good luck, as give her good luck to someone else. The more good luck she gives out, the more bad luck she has for herself.

I had an idea for a crafting (mundane, not magical items) character rolling in my head, and after checking the Homebrew Stunt list I noticed that there weren't any stunts aimed at hexing. Do you think a stunt similar to the following is plausible?

Hexproof: You are familiar with why and how technology gets hexed, and you know how to build around it. By using simple systems and multiple redundancies, your creations are more difficult to hex. Increase the difficulty by two whenever anyone/anything attempts to hex one of your creations, either by accident or on purpose.