Fix: Resolve "Multiple top-level packages" build error and Python version constraint

[AviJxn]

Problem

The current pyproject.toml lacks explicit package discovery configuration. On Windows and other fresh environments, pip install . fails because setuptools detects a flat-layout with multiple top-level packages (backend, frontend, data_processing) and cannot determine the package root ambiguity.

Additionally, the requires-python constraint (>=3.12) prevents installation on standard Python 3.11 environments, which are still widely used and compatible with the dependencies.

Solution

• Explicit Discovery: Added [tool.setuptools.packages.find] to explicitly include backend, frontend, and data_processing.
• Version Compatibility: Relaxed requires-python to >=3.11 to support a broader range of development environments.

Verification

• Before: pip install . crashed with error: Multiple top-level packages discovered.

• After: pip install . completes successfully, and all dependencies resolve correctly.

Fixes #36