Fix color preservation when changing prefix and add LibertyBans integration

- Fixed issue where gradient colors were lost when changing prefix
- Updated GradientGUIListener to preserve existing colors when setting prefix
- Updated GradientPrefixCommand to pass existing colors to confirmation GUI
- Added LibertyBans integration (simple version without API dependency)
- Added LibertyBans to softdepend in plugin.yml
- LibertyBans integration detects plugin presence but relies on LibertyBans own mute handling

src/main/java/com/loki/lochat/gradient/commands/GradientPrefixCommand.java

@@ -157,7 +157,9 @@ public class GradientPrefixCommand implements CommandExecutor, TabCompleter {
         }
 
         GradientConfirmGUI gui = new GradientConfirmGUI(module, player, 
-                GradientConfirmGUI.ConfirmType.PREFIX, data.getColors(), prefix, price);
+                GradientConfirmGUI.ConfirmType.PREFIX, 
+                data.hasColors() && data.isColorEnabled() ? data.getColors() : null, 
+                prefix, price);
         FoliaUtil.runEntityTask(module.getPlugin(), player, gui::open);
         return true;
     }