Use tenant specific endpoint

[zuhairmahd]

This pull request updates the authentication configuration to support both single-tenant and multi-tenant Entra ID (Azure AD) scenarios, improves environment variable flexibility, and updates documentation for clarity. It also adds a new CNAME for deployment.

Authentication configuration and environment variables:

• Updated src/utils/config.js to use VITE_ENTRA_CLIENT_ID as the primary client ID, with VITE_CLIENT_ID as a fallback for backward compatibility. The authority URL now uses VITE_ENTRA_TENANT_ID if set, enabling single-tenant support, or defaults to common for multi-tenant.

Documentation updates:

• Updated the README.md to reflect the new environment variables, clarifying the use of VITE_ENTRA_CLIENT_ID, VITE_ENTRA_TENANT_ID, and the optional VITE_CLIENT_ID for backward compatibility. The documentation now explains the purpose of each variable and when to use them. [1] [2]

[zuhairmahd]

@SkipToTheEndpoint Thanks for an interesting idea. I took it for a spin and realized that the documentation had a couple of issues:

1. The variable name the app is looking for is VITE_ENTRA_CLIENT_ID, contrary to what the documentation stated (VITE_CLIENT_ID).
2. Turns out you can't use a single tenant application without having to provide a tenant id, so I added the new environment variable VITE_ENTRA_TENANT_ID
3. The Github deploy action to Github pages is problematic, since for some reason Github seems to want to serve the code as text rather than Javascript, but I kinda gave up on that.

Thanks again.