[Playground] Playground auth with GitHub

[justinyoo]

• https://learn.microsoft.com/en-us/azure/container-apps/authentication
• https://learn.microsoft.com/en-us/azure/container-apps/authentication-github

[justinyoo]

• https://hajekj.net/2020/05/01/running-easyauth-locally/
• https://alanta.nl/posts/2024/02/dev-proxy-for-easy-auth-on-container-apps
• https://github.com/alanta/EasyAuthDevProxy
• https://johnnyreilly.com/azure-container-apps-easy-auth-and-dotnet-authentication