Module export 

Feature export module for aprender ML format.

Issue #2: Export CommitFeatures to aprender format

This module provides:

• Export CommitFeatures as aprender Matrix<f32>
• Export defect labels as Vec<u8> (18-category taxonomy)
• Parquet output support for large datasets
• Round-trip compatibility with aprender training pipeline

Implements extreme TDD: All tests written before implementation.

Structs

ExportMetadata

Metadata for exported dataset

ExportedDataset

Exported dataset for aprender ML training

FeatureExporter

Feature exporter for aprender format

Enums

ExportFormat

Export format for aprender integration

Constants

FEATURE_DIMENSION

Feature dimension for CommitFeatures (matches CommitFeatures::DIMENSION) NLP-014: Extended from 8 to 14 dimensions for CITL integration

NUM_CATEGORIES

Total number of defect categories (10 general + 8 transpiler)