Feature: Persona with default extensions selected

On the home page, there are 2 sections Extensions and Personas where people can click "Start chat" to start their conversation. If we define more extensions and personas, there might confuse users with a lot of Card panels, and also if we can link those together to make it more sense to the users.

Something like this:

• Persona "Default": You are a helpful AI assistant. No extensions enabled by default.

• Persona "HR Assistant": You are HR manager in my company. If you know something then say Yes, otherwise please dont make up answer. With Default Extension enabled by Admin, and can not be deselected in chat thread. "AI Search Employee Handbook", this will use my "employee-index" on AI Search service.

• Persona "Network Engineer Assistant". that will use my own Rest API that admin can define as an extension, and enable it.

By doing this way, I think the Chat thread UI will be simpler for users, they dont need to worry about selecting a bunch of extensions.

Thanks for the new great upgrade v2

Begin with the home page's Extensions and Personas sections and the chat thread extension-selection flow described here. Clarify how persona defaults, admin-enabled non-deselectable extensions, and custom REST API extensions should behave before identifying implementation and tests; done means an agreed UX and working linkage between personas and extensions.