When a lora_adapter path is provided, the trainer pre-generates
LoRA-distorted mels for each training clip (full ODE generation +
VAE decode) and trains the vocoder to produce clean audio from them.
This teaches the vocoder to compensate for LoRA latent distribution
shift without requiring perfectly aligned training pairs.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>