Both flags in unified_data_loader.rs config structs were declared and
defaulted but never read anywhere workspace-wide:
- DataProcessingConfig.enable_quality_filtering: set true, zero readers
- TrainingDataConfig.enable_augmentation: set false, zero readers
Deleted field + default at each of 2 sites. use_unified_extractor left
alone — it actively gates Option<UnifiedFeatureExtractor> at line 360.