What it does
Plays a short macOS system sound (Tink) on every transition between shaking and not shaking.
How it works
The engine watches its `isShaking` state for transitions and calls `NSSound(named: "Tink")?.play()` when it changes.
Where to find it
Settings → General → Play a sound when shaking starts or stops. Off by default.
When to use it
When you want to be aware in real time that Shake It On just started or stopped — for example, you're using strict conditions and want to know the moment they flip.