fix: resolve NameError and import pathing in main.py

[lokesh12344]

Description

This PR fixes two critical bugs in src/main.py that prevented the script from running successfully in a standard environment.

Changes

1. Fixed NameError: Added from typing import Union. The Union type hint was used on line 14 but was never imported, causing the script to crash immediately upon execution.
2. Fixed Import Pathing: Changed from controller import Controller to from src.controller import Controller. This ensures the script can be run from the project root directory (standard practice) without triggering a ModuleNotFoundError.

How to Verify

Before this fix, running python3 src/main.py from the root would result in:

• NameError: name 'Union' is not defined
• ModuleNotFoundError: No module named 'controller'

After this fix, the script successfully imports all dependencies and initializes the Controller.
Fixes #388

[lokesh12344]

Issue #388