Giveaway wheel

The Giveaway Wheel draws winners from a saved eligibility pool.

Recommended workflow:

1. 1.Create a snapshot.
2. 2.Review eligibility.
3. 3.Draw winners.
4. 4.Record winners.
5. 5.Assign prize roles if needed.
6. 6.Use rerolls only when required.

The backend should determine winners before the wheel animation displays them.