Improve blog editor source summary

src/TaxBaik.Web/Pages/Shared/_BlogEditor.cshtml

@@ -97,11 +97,17 @@
                     <span class="badge bg-secondary-lt text-secondary">공통 스타일</span>
                 </div>
                 <div class="card-body d-grid gap-3">
-                    <div>
+                    <div class="admin-editor-source">
                         <div class="text-muted small text-uppercase mb-1">불러온 원본</div>
-                        <div class="fw-semibold">@Model.Title</div>
-                        <div class="text-muted small">카테고리: @Model.CategoryId</div>
-                        <div class="text-muted small">발행: @(Model.IsPublished ? "예" : "아니오")</div>
+                        <div class="fw-semibold mb-2">@Model.Title</div>
+                        <dl class="row g-2 mb-0 small">
+                            <dt class="col-4 text-muted fw-normal">카테고리</dt>
+                            <dd class="col-8 mb-0">@Model.CategoryId</dd>
+                            <dt class="col-4 text-muted fw-normal">발행</dt>
+                            <dd class="col-8 mb-0">@(Model.IsPublished ? "예" : "아니오")</dd>
+                            <dt class="col-4 text-muted fw-normal">썸네일</dt>
+                            <dd class="col-8 mb-0">@(string.IsNullOrWhiteSpace(Model.ThumbnailUrl) ? "-" : Model.ThumbnailUrl)</dd>
+                        </dl>
                     </div>
                     <article class="content-prose blog-preview-pane" data-blog-preview>@Html.Raw(Model.Content)</article>
                 </div>

src/TaxBaik.Web/wwwroot/css/admin.css

@@ -1266,6 +1266,24 @@ textarea:focus-visible {
   margin-top: 0.25rem;
 }
 
+.blog-editor-shell .admin-editor-source {
+  padding: 0.875rem 1rem;
+  border: 1px solid var(--border-color-light);
+  border-radius: var(--radius-lg);
+  background: linear-gradient(180deg, #FFFFFF 0%, #F8FAFC 100%);
+}
+
+.blog-editor-shell .admin-editor-source dt {
+  color: var(--text-secondary);
+  font-size: 0.78rem;
+}
+
+.blog-editor-shell .admin-editor-source dd {
+  color: var(--text-primary);
+  font-size: 0.82rem;
+  overflow-wrap: anywhere;
+}
+
 /* ============================================================================
    Responsive Design - Mobile First
    ============================================================================ */