feat(attachments): list downloadable attachments on admin email detail page

The admin email detail view loaded the full email but never rendered its
attachments, so there was no way to download them from the admin UI (only
the public entry view and the feed enclosure exposed them).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/styles/components.css

@@ -787,6 +787,45 @@ table.table code {
   color: var(--color-text-secondary);
 }
 
+.attachments {
+  margin-top: var(--spacing-lg);
+  padding-top: var(--spacing-md);
+  border-top: 1px solid var(--color-border);
+}
+
+.attachments h2 {
+  font-size: var(--font-size-md);
+  margin: 0 0 var(--spacing-sm);
+}
+
+.attachment-list {
+  list-style: none;
+  padding: 0;
+  margin: 0;
+}
+
+.attachment-list li {
+  display: flex;
+  align-items: center;
+  gap: var(--spacing-sm);
+  padding: var(--spacing-xs) 0;
+}
+
+.attachment-list svg {
+  flex: 0 0 auto;
+  color: var(--color-text-secondary);
+}
+
+.attachment-list a {
+  color: var(--color-primary);
+  word-break: break-all;
+}
+
+.attachment-size {
+  color: var(--color-text-secondary);
+  font-size: var(--font-size-sm);
+}
+
 /* Compact copy-to-clipboard for table cells */
 .copyable.copyable-inline {
   margin-bottom: 0;