Harden best-of-N selection: reject dropouts and squashed takes

Fix H200 fp16 instability: pin MATH SDPA, fp32 autoencoder, no TF32

Fix ZeroGPU audio quality and stuck-processing UI

Restore the verified-good whole-buffer normalization

Fix ZeroGPU continuation: bound the lead-in, normalize the tail, shrink the GPU window

Rebuild CODA on Stable Audio 3 Small Music