Add: Authentication to Feature Flag Frontend

[MehulKChaudhari]

Issue Description

Add authentication to the feature flag frontend, similar to other RDS sites.

Expected Behavior

Users should be able to sign in using their GitHub accounts.

Current Behavior

The feature flag frontend currently lacks any authentication.

Steps to Reproduce

1. Visit the feature flag frontend.
2. Observe that there is no option to sign in.

Severity/Priority

• High

Additional Information

This aligns with the authentication pattern used across other RDS sites.

Thank you!