fix: move test modal to view body, wire button via addEventListener

Razor section forwarding across nested layouts is unreliable.
Modal div and script are now directly in Edit.cshtml body (not in
any section) so they are always in the DOM when the page renders.
Button uses addEventListener instead of inline onclick to decouple
from layout rendering order.

Ref: IT-628

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

HrynCo.NotificationService.Web/Views/Shared/_EditorLayout.cshtml

@@ -14,7 +14,3 @@
         </div>
     </div>
 </div>
-
-@section Scripts {
-    @RenderSection("Scripts", required: false)
-}