Creates a new AudioCapture instance.
Does not open the microphone — call start for that.
Capture settings (sample rate, chunk size, optional device ID).
Returns true if the microphone stream is currently live.
true when capturing, false when stopped or not yet started.
Registers the callback that will receive PCM audio chunks. Replaces any previously registered callback.
Invoked with each Float32Array PCM chunk.
Stops the audio stream and releases the microphone device so other browser tabs can acquire it.
Resolves once the stream is fully torn down.
Manages microphone access and streams raw PCM audio to a registered handler.