Update stamina model artifacts and metadata for demo

model_metadata.json

@@ -19,9 +19,9 @@
     "SDNN_sq"
   ],
   "target_col": "Fatigue_Level",
-  "cv_accuracy": 0.7906735751295336,
-  "cv_f1_score": 0.7899212989665266,
-  "training_accuracy": 0.9994818652849741,
-  "n_samples": 1930,
+  "cv_accuracy": 0.9096989966555183,
+  "cv_f1_score": 0.9097647105937559,
+  "training_accuracy": 0.998088867654085,
+  "n_samples": 2093,
   "training_mode": "all_data_demo"
 }