Evaluation: Adding User Authentication

[AkhileshNegi]

Is your feature request related to a problem? Please describe.
Evaluations currently use API keys for authentication. This works, but API keys are meant for programmatic/service-level access. For users running evaluations through the UI or directly, we should support proper user authentication instead.

Describe the solution you'd like
Add user authentication support for evaluations. Users should be able to run evaluations using their logged-in session rather than needing to pass an API key.