Provides a helper function `checkInternetConnexion` using the `connectivity_plus` package. It returns true for network types typically used for internet access (mobile, wifi, ethernet, vpn) and false otherwise.
Replaces hardcoded colors and standard Theme.of(context) accesses with a custom AppTheme.
Introduces distinct light and dark themes and persists the selected theme mode using shared_preferences.
Integrates the theme into the main app structure and applies it to various components and pages.
Adds google_fonts dependency for theme typography.