1. Monitoring kernel: prepend common_device_functions.cuh for DQN_ORDER_ACTIONS
2. Backtest metrics kernel: prepend common_device_functions.cuh
3. Backtest gather kernel: prepend common_device_functions.cuh
4. Backtest tx_cost: use training's transaction_cost_multiplier from hyperopt
(was hardcoded 0.1 bps — 17x lower than training's ~1.7 bps multiplier)
All standalone kernels now consistently include common_device_functions.cuh
for DQN action space defines. No more hardcoded constants.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>