Login v2

As a government employee, in order to access secure content on AI sharing platform, I would like to be able to use my government login credentials, giving me access to all platform content.

Features & Details:

1. Display login prompt when the user lands on the site
2. New users can create an account using their government email address
3. Existing users can login using their government credentials
4. User identify is verified upon providing the login credentials
5. Successful login grants access to platform content
6. Note 1: login.gov, max.gov, d2d.gsa.gov
7. Note 2: As a future enhancement, the content items might have different permission levels to access secure and public content fields/sections

No files, tests, or entry points are named. First inspect the existing site authentication flow and determine how login.gov, max.gov, or d2d.gsa.gov credentials can be integrated; done should include prompting users to log in, government-email account creation, identity verification, and access to platform content.

Written by the indexing model from the issue text.