Fix: Windows support for lore server by using subprocess.run

[mohsinkhan85090]

What

This pull request fixes the issue with running lore server on Windows. It updates the env.py and main.py to use subprocess.run instead of os.execv for invoking Flask, and ensures the correct path to flask.exe inside the virtual environment is used on Windows.

Why

Previously, running lore server on Windows failed with a FileNotFoundError because os.execv could not locate flask.exe. This change ensures cross-platform compatibility, allowing Windows users to run the server without errors.