The exposure aux loss now has its OWN Adam state (m, v, t) and updates
the exposure output weights INDEPENDENTLY from the main C51 optimizer.
No shared gradient buffer, no gradient clipping competition.
This is multi-task learning done right — each objective has its own
optimizer that doesn't interfere with the other.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>