Implement VIN-specific OCR extraction with optimized preprocessing: - Add POST /extract/vin endpoint for VIN extraction - VIN preprocessor: CLAHE, deskew, denoise, adaptive threshold - VIN validator: check digit validation, OCR error correction (I->1, O->0) - VIN extractor: PSM modes 6/7/8, character whitelist, alternatives - Response includes confidence, bounding box, and alternatives - Unit tests for validator and preprocessor - Integration tests for VIN extraction endpoint Co-Authored-By: Claude Opus 4.5 <[email protected]>