DSR portfolio reset and normalizer reset now happen via kernel flags
instead of CPU state mutation. Eliminates cudaStreamSynchronize at
epoch boundaries.
Also fix brace mismatch in gpu_training_guard.rs that left the
accumulate_q_value/read_q_accumulator/reset_q_accumulator methods
outside the impl block (introduced by Task 4 in-progress work).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
b122c2d0e7