mobilefacenet.cpp — Phase 3 placeholder

ggml port of MobileFaceNet for 128-d face embeddings.

Status: not started. See plugins/plugin-vision/VISION_RUNTIME_MIGRATION.md ("Phase 3 plan" / "MobileFaceNet (face embedding)") for the conversion strategy.

Replaces face-api.js::faceRecognitionNet (Inception/ResNet variant).

Reference checkpoint: deepinsight/insightface MobileFaceNet weights, MIT.

The embedding-compare logic in src/face-recognition.ts::euclideanDistance is reusable as-is; only the model load + forward pass need replacing.