v0.2.0 of human_security

On-device face liveness verification with ML Kit active challenges, TFLite anti-spoofing, and optional face identity matching. Changelog excerpt: - Face identity matching with bundled face_embedding.tflitemodel. - ReferenceImageSourcefor file, bytes, and URL reference images. - FaceMatchServiceand FaceMatchReportfor combined liveness + match results. - Optional referenceImageand matchThresholdon FaceLivenessDetector. - Front/back camera flip support. - Passive anti-spoof JPEG capture fallback. - Example app with reference image picker and result screen.