Restructure the repo for clarity

[jacobsimionato]

Let’s restructure the repo so that it tells our story of a modular system with a core specification and multiple consistent renderers, helper libraries, and tools.

Here is the proposed structure (update 7 Dec 2025):

• specification/0.8/
  • eval
  • json
  • docs
• samples
  • client
    • lit
      • contact
      • restaurant
    • angular
      • rizzcharts etc
  • agent
    • adk
      • restaurant etc
• renderers
  • lit
  • angular
  • flutter
    • README.md explains that the Flutter renderer is implemented in https://github.com/flutter/genui
    • samples note that this sample will be implemented in the A2UI repo and depend on the renderer library in the flutter/genui repo
• editor move this to the top level, because it is relevant to users of any agent library or renderer
• a2a_agent
  • python
    • a2ui_extension a shared library implementing the a2ui extension