VariantStrategy

Strategy for picking which variant fires on each `play()` : - `'random'` — uniform random pick. Cheap; can play the same one twice in a row, which sounds robotic. - `'no-repeat'` (default) — uniform random, but never the same as the previous pick. The fix every casino slot uses for SFX variants. - `'shuffle-bag'` — Tetris-style: cycle through every variant in a random shuffle, then reshuffle once the bag empties. Guarantees every variant gets played roughly equally.