3-panel side-by-side showing per-epoch trajectories of vanilla DFA vs
DFA + lambda*||f||^2 penalty:

  (a) ||h_L||:    vanilla 4e8 vs penalty 4e4 (4 OOM rescue)
  (b) ||g_L||:    vanilla 5e-10 vs penalty ~1e-6 (4 OOM rescue)
  (d) test acc:   vanilla 0.31 vs penalty 0.36 vs frozen baseline 0.349 vs BP 0.61

The visual story: (a) and (b) show the penalty pulling the diagnostics
back into the healthy regime, but (d) shows the rescue translates to
only +1 pp above the DFA-shallow baseline and 24 pp below BP-trainable.
The two failure modes (scale + direction) are visually separable: scale
is fixed, direction is not.

Together with figure_audit_5method.png and figure_cross_arch_temporal_s42.png,
this is the third paper-ready figure for §3-§4.