fix: Fix path for reasoning_agent_interactive.py

[normalian]

Purpose

• Fixed incorrect relative path for backend module import in reasoning_agent_interactive.py.
• This change ensures the interactive test harness can correctly import modules from the backend/v3 directory when executed from its current path.

Does this introduce a breaking change?

• Yes
• No

How to Test

1. Get the code

git clone https://github.com/normalian/Multi-Agent-Custom-Automation-Engine-Solution-Accelerator.git
cd Multi-Agent-Custom-Automation-Engine-Solution-Accelerator
git checkout fix/reasoning_agent_interactive.py

2. Run the interactive harness to confirm that the import path resolves correctly:

python .\src\tests\agents\interactive_test_harness\reasoning_agent_interactive.py

What to Check

Verify that the following are valid:

• The script starts without ModuleNotFoundError for v3.magentic_agents imports.
• Environment variables load correctly (no “not found and no default provided” errors related to path issues).

Other Information

• Only one line was modified to fix the relative path:
  • backend_path = Path(file).parent.parent.parent / "backend"
  • backend_path = Path(file).parent.parent.parent.parent / "backend"
• No functional logic or runtime behavior was changed beyond module path correction.

[Roopan-Microsoft]

Thanks @normalian for your contribution. We validated and yes its the right fix, Thanks.