Update README with V2 metrics and honest embedding assessment

V2 classifier (federal + foundation) - xgboost_model.json

V2 classifier (federal + foundation) - scaler.pkl

V2 classifier (federal + foundation) - label_encoders.pkl

V2 classifier (federal + foundation) - isotonic_calibrator.pkl

V2 classifier (federal + foundation) - feature_importance.json

V2 classifier (federal + foundation) - config.json

V2 classifier (federal + foundation) - README.md

initial commit