Remove debug code from login function and update password hashing method to use PBKDF2 in User model

app/models.py

@@ -38,7 +38,7 @@ class User(UserMixin, db.Model):
         Security: Uses bcrypt with automatic salt generation
         for resistance against rainbow table attacks.
         """
-        self.password_hash = password
+        self.password_hash = generate_password_hash(password, method='pbkdf2:sha256')
     
     def check_password(self, password):
         """