fix(admin): filter template keys by substring

Match both channels case-insensitively while keeping API and delivery lookups exact.

Ref: IT-1627

HrynCo.NotificationService.Web/Controllers/Admin/AdminTemplatesController.cs

@@ -27,10 +27,11 @@ public sealed class AdminTemplatesController(IMediator mediator, IEmailTemplateD
             ModelState.AddModelError("", previousError);
         try
         {
+            var filter = key?.Trim() ?? "";
             model.PushDefinitions = (await pushes.GetDefinitionsAsync(serviceId, ct))
-                .Where(d => string.IsNullOrWhiteSpace(key) || d.Key == key).ToList();
-            model.Definitions = (await definitions.GetDefinitionsAsync(service.Name, key, ct))
-                .Where(d => d.ServiceId == serviceId).ToList();
+                .Where(d => d.Key.Contains(filter, StringComparison.OrdinalIgnoreCase)).ToList();
+            model.Definitions = (await definitions.GetDefinitionsAsync(serviceId, ct))
+                .Where(d => d.Key.Contains(filter, StringComparison.OrdinalIgnoreCase)).ToList();
         }
         catch (Exception error) when (error is not OperationCanceledException)
         {

HrynCo.NotificationService.Web/Views/AdminTemplates/Index.cshtml

@@ -34,7 +34,7 @@
         <form method="get" action="/admin/services/@serviceId" class="template-key-filter">
             <label for="key" class="form-label fw-semibold">Template Key</label>
             <div class="template-key-filter-controls">
-                <input id="key" name="key" value="@keyFilter" class="form-control form-control-sm" placeholder="Filter by key" />
+                <input id="key" name="key" value="@keyFilter" class="form-control form-control-sm" placeholder="Filter by part of key" />
                 <button type="submit" class="btn btn-primary btn-sm">Filter</button>
                 <a href="/admin/services/@serviceId" class="btn btn-outline-secondary btn-sm">Clear</a>
             </div>