Continue refactoring

src/data/user_membership.rs

@@ -20,7 +20,7 @@ impl UserMembership {
         match self {
             UserMembership::Group(_, last_active) => *last_active,
             UserMembership::Friend(f) => f.last_activity_time,
-            UserMembership::Conversation(c) => c.last_active,
+            UserMembership::Conversation(c) => c.last_activity,
         }
     }
 }