Major changes from v1:
- Fix OFI data pipeline (ofi_gpu never wired, indices 42→66)
- Expand PORTFOLIO_STRIDE 30→38 for prev-OFI storage
- Add Mamba2 d_h_history backward (2 new cuBLAS GEMMs)
- Expose attention d_input_scratch for gradient flow
- Pre-compute OFI deltas in experience collection (state[74..82])
- Lower rank normalization threshold to 1e-5 for micro-rewards
- Use close-to-close return instead of unavailable open_price
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>