Sampled supplier, or re-apply per handle

A playback-wide setting — volume, speed, a fade factor, a filter curve — has to reach every player object that is alive right now and every one created later. There are two backend shapes, and they want opposite code.

Sampling backend. Each stream gets its own consumer, and every consumer closes over one shared field. Correctness comes from the factory, not from any push:

@Volatile private var currentCurve: EqualizerCurve = EqualizerCurve.FLAT

private fun createPlayer(): Player {
    val equalizer = EqualizerAudioProcessor { currentCurve }   // sampled per buffer
    …
}