add callback manager , model app

callbackmanager.py

@@ -88,6 +88,7 @@ def display_form(
     """
     return form
 
+# Initialize CallbackManager, fetching client_id and workspace_id from secrets
 CALLBACK_MANAGER = CallbackManager(
     redirect_uri="https://multitransformer-discharge-guard.hf.space/callback",
     client_secret=None  # Replace with actual secret if using a confidential client