- symbol field on DQNHyperparameters (default: "ES.FUT")
- TrainingSection.symbol in training profile TOML
- load_training_data scopes to symbol subdirectory
- dqn-smoketest.toml: lr=1e-5, cql_alpha=0.1, symbol=ES.FUT
- Pipeline tests: use smoketest profile, batch=32/buffer=1024 for RTX 3050
WIP: pipeline tests still NaN at step 22 with batch_size=64/buffer=5000.
Passes with batch=32/buffer=1024 (same as early_stopping test).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>