'..' parent row in the file list

Synthetic cursor-navigable first row (hidden at /) — Enter/double-click goes to
the parent like the toolbar button. Excluded from selection, rename, delete,
chmod, and transfers; shown with an up-arrow icon.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ui/src/app/file-panel/file-panel.ts

@@ -92,6 +92,7 @@ export class FilePanel {
   }
 
   iconFor(entry: FileEntry): string {
+    if (entry.name === '..') return 'mynaArrowUp';
     return entry.type === 'dir' ? 'mynaFolder' : 'mynaFile';
   }