Upgrade to Keras 3.x for model compatibility

app.py

@@ -17,9 +17,11 @@ from PIL import Image
 from joblib import load
 import xgboost
 import tensorflow as tf
-from tensorflow.keras.models import load_model
-from tensorflow.keras.layers import Conv2D, Multiply, Layer
-import tensorflow.keras.backend as K
+# Use Keras 3.x standalone imports
+import keras
+from keras.models import load_model
+from keras.layers import Conv2D, Multiply, Layer
+import keras.backend as K
 import radiomics
 
 # Suppress warnings
@@ -166,7 +168,7 @@ def focal_tversky_loss(y_true, y_pred, alpha=0.7, beta=0.3, gamma=4/3):
     return K.mean(focal_tversky)
 
 def combined_loss(y_true, y_pred):
-    return focal_tversky_loss(y_true, y_pred) + tf.keras.losses.BinaryCrossentropy()(y_true, y_pred)
+    return focal_tversky_loss(y_true, y_pred) + keras.losses.BinaryCrossentropy()(y_true, y_pred)
 
 # Load models
 print("[MODEL] Loading models into memory...", flush=True)