Fix Duplicate Prevention Display - Show Actual Campaign Setting Instead of Default 14 Days

Problem Description:

In the campaign settings, users can configure "Ignore duplicate requests" with a custom duration (e.g., 180 days).

However, the contact activity timeline always displays the default hardcoded message "an invitation has already been sent within the past 14 days" regardless of the actual campaign setting.

This creates confusion when users have set a different duplicate prevention window. The system should dynamically display the actual configured value (e.g., "within the past 180 days") instead of the hardcoded 14-day default.

Expected behavior: Display message should reflect the actual campaign setting