nx_audio_enhance.nx

nx_audio_enhance.nx -- sovereign AUDIO ENHANCEMENT for the call mic path: AGC (auto gain control -> boosts a quiet/bad mic to a healthy level, with a hard limiter so it never clips) + an adaptive VAD NOISE GATE (estimates the noise floor, attenuates frames that are just background hiss between speech). This is the "top-of-the-line audio even with a bad mic" path, pure Nishi -- the browser only ferries raw PCM; ALL DSP is here. Operates on signed PCM samples in an i64 array (-32767..32767). Spectral subtraction via nx_fft = the next rung (in-speech denoise); this rung delivers the two biggest bad-mic wins (level + background gating). license_tier: ORIGINAL