chore: upgrade jQuery from 3.6.1 to 4.0.0

The vendor file was misnamed jquery-1.12.4.min.js but contained v3.6.1.
Replaced with the correctly-named jquery-4.0.0.min.js (78 KB, up from 89 KB).

Compatibility check: none of the removed jQuery 4.0 APIs are used in
main.js — no $.isArray, $.isFunction, $.trim, $.type, $.parseJSON, etc.
All ajax/deferred/DOM methods in use ($.ajax, $.when, .done/.fail/.always,
.on, .prop, .css, .addClass etc.) remain in the full 4.0 build.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/wwwroot/index.html

@@ -216,7 +216,7 @@
         </div>
     </div>
     <a href="#" id="cookieManage" class="cookie-manage btn btn-dark btn-sm shadow" style="display:none;" data-i18n="cookies.settings">Cookie settings</a>
-    <script src="/js/vendor/jquery-1.12.4.min.js"></script>
+    <script src="/js/vendor/jquery-4.0.0.min.js"></script>
     <script src="/js/bootstrap.min.js"></script>
     <script src="/js/main.js"></script>
 </body>