Windows support (without growl)

See https://github.com/go-toast/toast

The issue references an external library (go-toast/toast) for Windows notifications. First, examine the current notificator codebase to understand its architecture and how it integrates with OS-specific notification systems. Then, research the linked library to see how it implements Windows toast notifications without Growl. The goal is to add a Windows backend that uses this library, ensuring it works alongside existing implementations for other OSes.

Scritto dal modello di indicizzazione a partire dal testo della issue.