Synthetic regression fixture generated from the revised manuscript implementation,
using 48 synthetic observations, J=4, 1000 Gaussian draws, seed=874,
and the default slope grid and alpha. No patient records are included.
The independent matrix and brute-force tests do not rely on this fixture.

Source SHA-256:
06b5246315bbd6c46edd603da178040e5948e3126825dc491d696705fe3a696b  direct_band_lib.R
5ce8603853bb878a0880505c5c654c676171b62add91f6b9f0940b398dbca695  direct_band.cpp
