WP-1325 out of sample: TOPAS laws on WO3 refitted alone, against the untied fit
machine   Darwin arm64, 10 CPUs, python 3.12.10, numpy 2.5.4
rietx     1.10.0.dev0 at 506c340a, compiled kernels on
load      80.47 74.60 73.98
laws      ['t_beta', 'p_c'], each alone over all 100 patterns
t_beta    3248.0 s converged iters [2, 4, 28, 184]; χ² 1337266.5 with 2903 free; alone    110.1 /  97 dof (cut  121.0,  1.14/dir, p 0.171) keep

the comparison, from the per-law lines in wo3_each2_results.txt
against the untied fit read from wo3_form_results.txt: χ² 1333788.3 with 3000 free, χ²r·f² 19.253; the all-laws fit's χ²r·f² 19.577
  t_beta   refit Δχ²    3478.2 for  97:   180.7 (1.86/dir, p 5.42e-07)
           all-laws freed 110.1 /  97 dof (cut  121.0,  1.14/dir, p 0.171) keep; its gain    2155.5 (0.62 of the refit)
           the law-alone fit's own reading 110.1 /  97 dof (cut  121.0,  1.14/dir, p 0.171) keep
