Add Toasts/Snackbars for Backend Errors and Network Status

[bryanngongeh]

Implement a mechanism (e.g., a simple context + useToasts() hook or a lightweight component) to display toasts or snackbars for backend errors and network status updates to the user.

• Acceptance Criteria:

• When a backend error occurs, a clear toast/snackbar message is displayed to the user.

• Network status changes (e.g., offline/online) are communicated via toasts/snackbars.

• Toasts/snackbars are non-intrusive and disappear after a short duration.