feat: Robust environment scanner

[AnouarMohamed]

Closes #19.

This PR brings the core environment scanner up to the robustness standards of the rest of the toolkit:

• Pathlib Integration: Moves away from fragile string-based path manipulation to robust pathlib.Path objects.
• Performance Optimization: Prunes the directory tree during traversal, skipping heavy folders like node_modules or target entirely rather than just filtering their contents.
• Accurate Detection: Uses set-based marker detection to identify Spring, Angular, and Vue projects more reliably, especially in complex nested environments.