refactor: use .on() for keyup event in search input handler

Update the search input's  binding to use  instead of the deprecated shorthand , aligning with our consistent event binding pattern.

This change keeps the codebase uniform with recent refactors (e.g., click, focus, keydown) and prepares for safe compatibility with jQuery 3.x now that we've upgraded.

No behavioral changes event logic and timing remain identical.

Part of ongoing effort to eliminate legacy jQuery patterns ahead of removing jQuery Migrate.

Author: RafaelJohn9

assets/js/application.js

@@ -190,7 +190,7 @@ var Search = {
   },
 
   observeTextEntry: function() {
-    $('form#search input').keyup(function(e) {
+    $('form#search input').on('keyup', function() {
       Search.runSearch();
     });