Security: Remove hardcoded HF token, use environment variable only

- Remove hardcoded token from code for security
- Token now only sourced from HF_TOKEN environment variable
- Maintains proper authentication while keeping token private
- Updated error handling to guide users on token setup

app.py

@@ -36,9 +36,17 @@ class DermaAIModel:
         """Load the DermaAI model from Hugging Face Hub using Keras 3.0"""
         try:
             print("🔄 Loading DermaAI model from Hugging Face...")
-            # Load model directly from Hugging Face using Keras 3.0
-            self.model = keras.saving.load_model("hf://Siraja704/DermaAI")
-            print("✅ Model loaded successfully!")
+            # Get authentication token from environment variable only (secure)
+            hf_token = os.getenv("HF_TOKEN")
+            
+            if hf_token:
+                # Load model with authentication
+                self.model = keras.saving.load_model("hf://Siraja704/DermaAI", token=hf_token)
+                print("✅ Model loaded successfully with authentication!")
+            else:
+                # Try loading without token (if model becomes public)
+                self.model = keras.saving.load_model("hf://Siraja704/DermaAI")
+                print("✅ Model loaded successfully!")
         except Exception as e:
             error_msg = str(e)
             print(f"❌ Error loading model: {e}")