Add comprehensive architecture documentation to README.md

[Copilot]

This PR enhances the README.md with detailed documentation about the Sustineo architecture, addressing the request to explain the system's organization and communication patterns.

Added Documentation

• Architecture Overview: Explains how Sustineo is built on a multi-agent architecture with a central voice agent maintaining global context
• Agent Types and Capabilities: Documents the three agent types (Foundry, Custom, Function) and lists six specific agent roles in the system
• Architecture Diagrams:
  • System component diagram showing relationships between frontend, backend, and agent components
  • Sequence diagram illustrating the interaction flow between user, UI, and agents
• Communication Patterns: Details how agents interact, including voice agent orchestration, function calling mechanism, and WebSocket communication
• Implementation Technologies: Lists the key technologies used in both backend and frontend

The documentation now provides a clear explanation of how the application's six agents work together, with special emphasis on the voice agent's global context role and how the other agents maintain more localized contexts.

Fixes #36.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[msabramo]

Okay, this looks awesome although I've only scanned what it did and not read it in depth yet (which I will try to do in a bit). But first, I have some "meta" ideas that are more of a feature request than about this PR per se...

Whenever I change a README.md I like to grab a link to the rendered README and put it in the PR so I and the reviewers can check it and make sure it's well-formatted and doesn't have a non-closed triple backticks, bolding, etc. It's actually kind of a pain to do it because I have to open the branch and navigate to it and then navigate back to the PR or switch tabs and it's not rocket science but it's also just friction. Most developers on my team don't even bother with this, because they're not as obsessive as me. 😄

Anyway, it would be awesome if Copilot recognized that it's changing README.md (or perhaps any Markdown file?) and generated this link to the rendered markdown and put it in a comment or in the PR description or maybe even in a new area in the right sidebar of the PR for "Documentation"?

[msabramo]

Whenever I change a README.md I like to grab a link to the rendered README and put it in the PR so I and the reviewers can check it and make sure it's well-formatted

In case I wasn't clear here, the URL for this PR would be this:

https://github.com/sethjuarez/sustineo/blob/copilot/fix-36/README.md

We can click it and see how it looks for reals with all the formatting that humans like.

[msabramo]

OK this looks great to me, although the creators should definitely make sure this reflects the architecture accurately and doesn't say anything false.

[msabramo]

Bump

[msabramo]

:excited:
Would love to see this updated as needed and merged because I'd like to point to this at my company (Adobe) as an example of how to do a multi-agent app, but it's very hard for people to understand it. I understand it somewhat because I went to the Microsoft Build session (and was impressed!) but now I see the opportunity to use this project as a tool to drive adoption of Azure AI Foundry agents but at the moment if I send the URL of this repo to folks, I don't think they'll be able to understand the coolness of this the way I do. So it's important I think to make the README awesome so that people who come to this see it for how cool it is.