Refactor orchestration to use event-based callbacks

[Fr4nc3]

Replaces legacy callback attachment with unified event-based handling for Magentic workflow events. Removes internal callback adapter methods and updates workflow construction to use .on_event() for streaming and final agent responses, improving maintainability and aligning with agent_framework best practices.

Purpose

• ...

Does this introduce a breaking change?

• Yes
• No

How to Test

• Get the code

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

• Test the code

What to Check

Verify that the following are valid

• ...

Other Information