What frontend framework does Graylog use and can I add custom JavaScript?

I’m trying to figure out what technology stack Graylog uses for its web interface. I want to add some custom JavaScript code to track user sessions and need to understand the frontend architecture better.

Is it possible to inject JS snippets directly into the Graylog UI? Or would it be better to put a reverse proxy like Nginx in front of it to handle this kind of customization?

Any insights about Graylog’s frontend components would be really helpful. Thanks in advance for any guidance you can provide.