Adds PerimeterToAreaRatio (perimeter / area) as a spacing sensitivity
indicator for ML feature extraction.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Add FeatureExtractor for computing geometric part features (convexity,
aspect ratio, circularity, bitmask) and BruteForceRunner for generating
training data by running the fill engine and recording results.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>