Add debug log message about auth mode

Author: YuriiMotov

src/fastapi_cloud_cli/commands/deploy.py

@@ -691,6 +691,10 @@ def deploy(
     identity = Identity()
     use_deploy_token = identity.has_deploy_token()
     has_auth = use_deploy_token or identity.is_logged_in()
+    
+    logger.debug(
+        "Authentication mode: %s", "deploy token" if use_deploy_token else "user token"
+    )
 
     with get_rich_toolkit() as toolkit:
         if not has_auth: