feat(notification): add admin rest management and deletion

Add revision-safe service and template APIs, channel mapping, and validated admin controls.

Ref: IT-1601

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

@@ -0,0 +1,17 @@
+@using HrynCo.NotificationService.Web.Controllers.Admin.ViewModels
+@model EmailTemplateDefinitionDeleteViewModel
+@{ ViewData["Title"] = "Delete email template"; var returnUrl = Url.Action("Index", "AdminTemplates", new { serviceId = Model.ServiceId, key = Model.KeyFilter }); }
+<div class="admin-delete-confirmation">
+<nav aria-label="Breadcrumb"><ol class="breadcrumb"><li class="breadcrumb-item"><a href="/admin/services">Services</a></li><li class="breadcrumb-item"><a href="@returnUrl">@Model.ServiceName</a></li><li class="breadcrumb-item active" aria-current="page">Delete template</li></ol></nav>
+<h2>Delete template @Model.Key?</h2>
+<div asp-validation-summary="All" class="text-danger" role="alert"></div>
+<div class="alert alert-danger">This permanently deletes the definition, shared variables and <strong>@Model.LanguageCodes.Count translation(s)</strong> from service @Model.ServiceName.</div>
+<p>Languages: @(Model.LanguageCodes.Count == 0 ? "No translations" : string.Join(", ", Model.LanguageCodes))</p>
+<p>The service, its language catalog and email channels are retained.</p>
+<form asp-action="DeleteDefinition" asp-route-serviceId="@Model.ServiceId" asp-route-definitionId="@Model.DefinitionId" method="post">
+    @Html.AntiForgeryToken()
+    <input asp-for="Revision" type="hidden" /><input asp-for="KeyFilter" type="hidden" />
+    <div class="form-check mb-3"><input asp-for="ConfirmDelete" class="form-check-input" /><label asp-for="ConfirmDelete" class="form-check-label">I confirm deletion of @Model.Key and its @Model.LanguageCodes.Count translation(s).</label></div>
+    <div class="d-flex flex-wrap gap-2"><button type="submit" class="btn btn-danger">Delete template</button><a class="btn btn-secondary" href="@returnUrl">Cancel</a></div>
+</form>
+</div>

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

@@ -86,7 +86,7 @@
                 <div class="template-preview-section-title">Rendered subject</div>
                 <div id="previewSubject" class="template-preview-subject"></div>
                 <div class="template-preview-section-title mt-3">Rendered HTML</div>
-                <iframe id="previewHtmlFrame" class="template-preview-frame" sandbox="" referrerpolicy="no-referrer" title="Email HTML preview"></iframe>
+                <iframe id="previewHtmlFrame" class="template-preview-frame" sandbox="allow-same-origin" referrerpolicy="no-referrer" title="Email HTML preview"></iframe>
                 <div class="template-preview-section-title mt-3">Rendered text</div>
                 <pre id="previewText" class="template-preview-text mb-0"></pre>
             </div>
@@ -98,5 +98,6 @@
     <a id="cancelTemplate" href="@Url.Action("Index", "AdminTemplates", new { serviceId = Model.ServiceId, key = Model.KeyFilter })" class="btn btn-secondary">Cancel</a>
 }
 @section Scripts {
+    <script src="~/js/email-template-preview.js" asp-append-version="true"></script>
     <script src="~/js/email-template-editor.js" asp-append-version="true"></script>
 }

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

@@ -5,9 +5,9 @@
     var serviceId = Model.Service.Id;
     var keyFilter = Model.KeyFilter;
 }
-<nav aria-label="Breadcrumb"><ol class="breadcrumb"><li class="breadcrumb-item"><a href="/admin/services">Services</a></li><li class="breadcrumb-item active" aria-current="page">@Model.Service.Name</li></ol></nav>
+<nav aria-label="Breadcrumb" class="service-template-breadcrumbs"><ol class="breadcrumb"><li class="breadcrumb-item"><a href="/admin/services">Services</a></li><li class="breadcrumb-item active" aria-current="page">@Model.Service.Name</li></ol></nav>
 <div class="page-header">
-    <h2>@Model.Service.Name</h2>
+    <h2 class="service-template-service-name">@Model.Service.Name</h2>
     <a href="/admin/services/@serviceId/edit" class="btn btn-outline-primary">Edit Service</a>
 </div>
 <div class="service-template-catalog mb-3" aria-label="Configured service languages">
@@ -29,7 +29,7 @@
     <a asp-action="Create" asp-route-serviceId="@serviceId" asp-route-keyFilter="@keyFilter" class="btn btn-primary">Create template</a>
 </div>
 <div asp-validation-summary="All" class="text-danger mb-3" role="alert"></div>
-<div class="table-responsive"><table class="table table-hover service-template-grid"><thead><tr>
+<div class="table-responsive"><table class="table table-hover admin-data-table service-template-grid"><thead><tr>
     <th scope="col">
         <form method="get" action="/admin/services/@serviceId" class="template-key-filter">
             <label for="key" class="form-label fw-semibold">Template Key</label>
@@ -45,7 +45,20 @@
 </tr></thead><tbody>
 @if (Model.Definitions.Count == 0)
 {
-    <tr><td colspan="3">No email templates found for this service.</td></tr>
+    <tr><td colspan="3"><div class="empty-state">
+    @if (!ViewData.ModelState.IsValid)
+    {
+        <p class="mb-0">Templates are unavailable. Review the error and try again.</p>
+    }
+    else if (!string.IsNullOrWhiteSpace(keyFilter))
+    {
+        <i class="bi bi-search" aria-hidden="true"></i><p class="mt-2 mb-0">No templates match this key.</p><a href="/admin/services/@serviceId" class="btn btn-primary btn-sm mt-3">Clear filter</a>
+    }
+    else
+    {
+        <i class="bi bi-envelope" aria-hidden="true"></i><p class="mt-2 mb-0">No email templates for this service yet.</p><a asp-action="Create" asp-route-serviceId="@serviceId" class="btn btn-primary btn-sm mt-3">Create First Template</a>
+    }
+    </div></td></tr>
 }
 @foreach (var template in Model.Definitions)
 {
@@ -71,7 +84,7 @@
                 </ul>
             }
         </td>
-        <td class="template-actions"><a href="@editUrl" class="btn btn-outline-primary btn-sm" aria-label="Edit template @template.Key">Edit</a></td>
+        <td class="template-actions"><div class="list-action-links"><a href="@editUrl" class="btn btn-outline-primary btn-sm" aria-label="Edit template @template.Key">Edit</a><a asp-action="ConfirmDefinitionDelete" asp-route-serviceId="@serviceId" asp-route-definitionId="@template.Id" asp-route-keyFilter="@keyFilter" class="btn btn-outline-danger btn-sm" aria-label="Delete template @template.Key">Delete</a></div></td>
     </tr>
 }
 </tbody></table></div>