Experiment: polyatomic+polyatomic on boilingpoint

FOLD 1/5
RMSE: 51.6539, MAE: 33.6179, R2: 0.6318

FOLD 2/5
RMSE: 48.4909, MAE: 33.5824, R2: 0.6860

FOLD 3/5
RMSE: 50.8034, MAE: 34.7265, R2: 0.6569

FOLD 4/5
RMSE: 49.6399, MAE: 34.2908, R2: 0.6607

FOLD 5/5
RMSE: 52.4927, MAE: 36.6232, R2: 0.6316

====== K-FOLD SUMMARY ======
RMSE: 50.5846  [49.4130, 51.8170]
MAE: 34.5713  [33.7383, 35.6440]
R2: 0.6534  [0.6368, 0.6701]

★ Using fold 2 model for test inference
RMSE: 48.2116, MAE: 33.3949, R2: 0.6859

====== HELD-OUT TEST METRICS ======
{'rmse': 48.211554672155614, 'mae': 33.394927978515625, 'r2': 0.6859204173088074}
Test RMSE: 48.1815  (95 % CI: 42.9072–53.9047)

Test MAE : 33.3759  (95 % CI: 29.6556–37.1169)

Test R²  : 0.6824  (95 % CI: 0.6007–0.7504)