v0.1.5 - Model Persistence & Economic Labeling Guardrails

Highlights v0.1.5

• Economic Guardrails: Positive-drift states can no longer be assigned to HIGH_VOL_BEAR or RISK_OFF.
• Model Persistence: Added \FittedRegime.save()\ and \FittedRegime.load()\ using np.savez_compressed + JSON.
• Causal Daily Inference:
  un_single_asof\ now accepts \itted\ models to run causal Hamilton filtering without retraining.