docs(ear-feedback): superfreak/hammer kit audition — sub-only bass, BCDA loop rotation, demucs vocal high-pass

PLN's on-disk verify of the forged kits, with measured confirmation of all
three reactions: bass_deep is a pure-sub layer (99% <150 Hz at −12.8 dBFS —
equal-loudness invisibility, not a level bug); loops are bar-exact but
musically ROTATED (strongest onset lands on beat-slot 1/2/4 instead of 0;
other_skank opens −23 dB below its own peak 30 ms — the 'cut DABC' feel);
vox thinness is htdemucs routing vocal low end into bass/other (vocal stems
carry ~0 energy <150 Hz). Fix directions logged: rotate-to-downbeat export
post-pass, BS-Roformer vocals re-cut, harmonic-saturation bass variant.