[Enhancement] Update Navbar to Display User's Name Upon Login

[AntGa]

Problem

Currently, the navbar gives the impression that users are always logged in, and there is no feedback when a user successfully logs in. This lack of dynamic feedback can be confusing. Updating the navbar to display the user's name when they are logged in will improve the user experience and provide clearer login status.

Objectives

• Modify the navbar to dynamically display the user's name when they are logged in.
• Ensure that the navbar correctly updates when a user logs out or when no user is logged in.
• Add a clear visual indication that reflects the user's login state.

Acceptance Criteria

• 1. The navbar displays the logged-in user's name.
• 2. The navbar dynamically updates to show login status (logged in vs logged out).
• 3. Documentation updated to explain how the navbar login feedback works.