Object pool

Recycling symbols to avoid GC pressure.

Where: pixi-reels' ObjectPool<T>.

The rule: symbols, frame contexts, event payloads — things that flow through the ticker — live in pools. Allocate on cold start; recycle on every cycle.

Watch for: references escaping the pool. A symbol that ends up in a bigwin presenter and isn't returned leaks. Use the Disposable pattern to enforce return.