Both walk-forward and full-training data loading paths now use rayon
par_iter to parse MBP-10 .dbn files concurrently. Previously 9 files
were parsed sequentially (~4 min on H100); parallel loading gives
~7-9x speedup proportional to file count. Trade file loading also
parallelized. Removed dead collect_dbn_files helper (superseded by
collect_dbn_files_recursive at module scope).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>