[Improvement] Gauzy Timer | Offline Mode | Notification when no internet connection. Must work on Windows, Linux and Mac

[ariefgp]

As a user, I want the app to detect when there's no internet connection and notify me that it's operating in offline mode, so I'm aware of the current operating status.
This feature must work on Windows, Linux and Mac. Please test on those operating system if possible to make sure the stability.

Description:

The app should detect when there's no internet connection and notify the user about operating in offline mode.

Detailed Flow:

1. User opens the app or is actively using it
2. App detects loss of internet connection
3. App switches to offline mode
4. User receives a notification about offline mode
5. UI updates to indicate offline status

Acceptance Criteria:

• App accurately detects loss of internet connection within 30 seconds
• User receives a clear, non-intrusive notification about offline mode
• The UI visibly indicates the offline status (e.g., an icon in the header)
• Notification disappears after user acknowledges it
• App detects when internet connection is restored and switches back to online mode
• User is notified when the app returns to online mode

Additional Notes:

• Consider how to handle intermittent connectivity
• Ensure the notification doesn't disrupt ongoing time tracking