The GPU PER replay buffer had a hardcoded 4 GB MAX_BYTES limit that
rejected the auto-sizer's 10M-entry proposal on H100 (80 GB VRAM).
Now per_max_buffer_bytes() computes 20% of total VRAM (min 1 GB) and
flows through OptimalReplayConfig → DQNConfig → GpuReplayBufferConfig
so both subsystems agree on the budget.
Also fixes misleading regime detection log (indices 211/219 → 40/41)
and renames dqn_config_2025 → dqn_default_config.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>