v0.5.0

Added

• Documentation site (mdBook, site/, published to GitHub Pages by .github/workflows/pages.yml): install guides,
  both repositories' docs, the NAM / IR analysis with an interactive re-amp comparison, and the API reference.

Changed

• nam::optimise: the loss now weights frequencies so each octave counts about the same
  (Options::weighting, Weighting::Octave, the new default). The old flat weighting gave the bottom octave
  ~0.5% of the fit, and imports came out 5–10 dB short at 50–160 Hz. In simulation the low-end error (40–160 Hz)
  of the Ampeg SVT-VR Classic (Normal) model drops from 4.9 to 2.1 dB rms and the frequency response error from
  2.5 to 1.2 dB; the frequency response improves on all six models tried, the low end on five (docs/05, "Low
  end"). Weighting::Flat keeps the old loss;
  example nam_optimise --flat. On hardware, a bass DI re-amped through the pedal against the
  model and IR in software: low end 5.2 → 3.8 dB rms, overall tone 3.5 → 2.8 dB (2.1 dB with the IR change below).
• ir::convert_optimised: the tap fit now covers 30 Hz – 16 kHz instead of 25 Hz – 20 kHz. Cab IRs have next to
  nothing above 16 kHz, and matching it cost taps the rest of the range needs: on fifteen Ampeg IRs the 1/3-octave
  error of what the pedal plays drops from 2.42 to 2.18 dB rms (better on 13; the two DI recordings get slightly
  worse), and the 40–160 Hz error from 3.55 to 2.90 dB.