fix: clear sort tag fields synchronously before async fill

Sort tag fields were not reset when opening a new song's edit modal,
so values from the previously opened song persisted until the async
romaji index fetch completed (or indefinitely if it found no entry).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ui.js

@@ -352,6 +352,12 @@ export function toggleInfoEdit() {
   document.getElementById('ie-disc').value        = s.discNumber   || '';
   document.getElementById('ie-totaltracks').value = s.albumSongCount || '';
 
+  // Clear sort fields immediately so stale values from a previously opened song don't show
+  document.getElementById('ie-titlesort').value       = '';
+  document.getElementById('ie-artistsort').value      = '';
+  document.getElementById('ie-albumartistsort').value = '';
+  document.getElementById('ie-albumsort').value       = '';
+
   // Sort tags: fetch romaji index on demand (cached if already loaded), then overwrite with
   // actual file tags from backend. This works regardless of the showRomaji toggle.
   const _sId = s.id;