feat: add filtering by ServiceName and Key in email templates query and UI

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

@@ -2,6 +2,8 @@
 @model IReadOnlyList<EmailTemplate>
 @{
     ViewData["Title"] = "Email Templates";
+    var serviceNameFilter = ViewData["ServiceNameFilter"] as string ?? string.Empty;
+    var keyFilter = ViewData["KeyFilter"] as string ?? string.Empty;
 }
 
 <div class="page-header">
@@ -11,6 +13,33 @@
     </a>
 </div>
 
+<div class="card shadow-sm mb-3">
+    <div class="card-body">
+        <form method="get" action="/admin/templates" class="row g-2 align-items-end">
+            <div class="col-12 col-md-5">
+                <label class="form-label fw-semibold" for="serviceName">Service Name</label>
+                <input id="serviceName"
+                       name="serviceName"
+                       value="@serviceNameFilter"
+                       class="form-control"
+                       placeholder="Filter by service name" />
+            </div>
+            <div class="col-12 col-md-5">
+                <label class="form-label fw-semibold" for="key">Key</label>
+                <input id="key"
+                       name="key"
+                       value="@keyFilter"
+                       class="form-control"
+                       placeholder="Filter by key" />
+            </div>
+            <div class="col-12 col-md-2 d-flex gap-2">
+                <button type="submit" class="btn btn-primary w-100">Filter</button>
+                <a href="/admin/templates" class="btn btn-outline-secondary w-100">Clear</a>
+            </div>
+        </form>
+    </div>
+</div>
+
 @if (!ViewData.ModelState.IsValid)
 {
     <div class="alert alert-danger">