scripts/fatness.py measures momentary bass fatness of rendered files with
the final model from Schmedeke's dissertation (section 5.4.3, adjusted R²
.773): two logistic terms on the C-weighted level and the MPEG-7 harmonic
ratio below 200 Hz, over 50 ms windows, after normalising to -23 LUFS
(BS.1770 integrated, gated).
The thesis does not state the dB(C) of its reference, so --offset maps
dBFS to dB(C) (default 100). On the seven Devath references, drops read
4-6, breakdowns near 0, and kick gaps show as 50 ms dips; SPL<200 medians
of 67-69 dB(C) suggest the offset may be 2-5 dB low.
Also corrects docs/ideas.md, which quoted the thesis's preliminary linear
model instead of the final one.
