Saturate floating audio before converting it to integer PCM

Neural audio decoder output must be clipped to the normalized sample range before conversion to signed integer PCM. Casting an out-of-range float directly does not saturate; it can wrap across the integer boundary and invert sample polarity, creating severe audible corruption even when generation itself is correct. Test synthetic values beyond both limits through the real streaming frame conversion, and assert the extremes clamp instead of wrapping.

Applies when: floating model output is serialized as signed integer PCM without a saturating codec helper. Keywords: audio distortion PCM int16 clipping saturation overflow wrap