StuckTerminationWrapper: add low_speed_threshold + max_low_speed_seconds params.
Car pinned against a barrier has speed≈0 even while sliding laterally — lateral
drift was resetting the position-based displacement timer, leaving the car stuck
for up to max_episode_seconds. Speed-based check terminates after 2s at speed<0.5.
Exp24: 7-bin discrete steering (DiscretizedActionWrapper) eliminates Gaussian policy
noise that caused rapid oscillation in exp23. max_episode_seconds reduced to 30s
since speed-based stuck detection now handles the barrier-contact cases.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Paul Huliganga