- Add external_app field to AuthWrapper class
- Get externalApp from website object during authentication
- For FileAccessToken: Use Websites.externalApp
- For API Key: Use WPSites.owner.externalApp
- Update all 5 file operation endpoints to use file_token.external_app
- scanner_backup_file
- scanner_get_file
- scanner_replace_file
- scanner_rename_file
- scanner_delete_file
- Ensures externalApp matches wp_path since they come from same source
- Fixes backup API failing due to incorrect user context