c53ea5517c
Adds L1 loss on real, imaginary, and magnitude STFT components across three resolutions (FA-GAN, arXiv:2407.04575). Penalizes phase smearing directly — magnitude-only losses cannot distinguish correct spectrum with wrong phase from a smeared spectrum. Controlled by lambda_phase (default 1.0, 0 = disabled). Applied on top of both the discriminator FM path and the fallback mel+STFT path. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>