With num_atoms=101 (just above the old threshold of 100), QR-DQN activated
alongside C51, doubling distributional computation. H100 epochs went from
~2s to ~35s. Raised threshold to 200 so num_atoms=101 uses C51 only.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>