Step 6: select xgboost_tuned as final model with full comparison and reasoning in README

Step 6: switch to CatBoost as final model, add tune_catboost.py, rename xgboost_final to xgboost_tuned

Step 6: model comparison charts, XGBoost GridSearchCV tuning, real benchmark scores in README

Step 5: remove SVM/KNN/MLP, clarify 10 pkl files in models dir (9 models + scaler)

Step 1: project setup, folder structure, and environment