plan_noise_inject is the ONLY new kernel inside graph_mega vs the
working 11b1a1ca9. Everything else is identical (submit_forward_ops_main,
submit_aux_ops, capture_graph_mega). If this fixes the hang,
plan_noise_inject is incompatible with graph_mega on sm_90.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>