pigroupe/SfynxCmfBundle ? reverse-engineered prompt

Build me a reusable Symfony 3 and 4 bundle for app authentication and back office user management. I want it to handle users, roles, permissions, and groups in a flexible way so access can be managed dynamically instead of being hard coded. It should plug into the Symfony security system with a user provider, and it should include the usual auth flow behavior for login success, login failure, logout, and exception handling.

Please also give it a simple admin dashboard where an admin can manage users and their access settings. Keep it installable as a bundle in an existing Symfony app, with clear setup instructions and sensible default configuration. PHP 7.2 or newer is fine.

If it helps, add fixtures for sample users and some basic automated tests so the main auth behavior can be verified quickly. Keep the code organized and practical for a real project, and look up current Symfony bundle docs online if you need to fill in missing details.