Per-sensor leave-one-out diagnostic.
Residual and origin-time fields are seconds. Position delta is metres. score
is max(abs(residual_s), abs(leave_one_out_residual_s)) / timing_sigma_s, or
abs(residual_s) / timing_sigma_s when the leave-one-out solve is unavailable.
Robust downweighting is reported only in loss_weight.