Eliminate all 26 Candle Tensor references from signal_adapter.rs.
Three functions (ppo_to_exposure_scores, signal_to_action_scores,
tft_quantile_to_signal) now take CudaSlice<f32> + CudaStream and
return CudaSlice<f32>, backed by three fused CUDA kernels in
signal_adapter_kernel.cu. Dead code evaluate_supervised_gpu_backtest
removed (zero callers). Added cuda_f32_to_tensor helper to
gpu_action_selector for DtoD copy back to Candle Tensor at API
boundaries (PPO hyperopt adapter, evaluate_baseline example).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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