fix tile size textfield

lib/main.dart

@@ -110,7 +110,6 @@ class _AnnotatorHomePageState extends State<AnnotatorHomePage> {
       setState(() => _isDraggingOver = false);
       if (event is html.MouseEvent) {
         final dt = event.dataTransfer;
-        if (dt == null) return;
         final files = dt.files;
         if (files == null || files.isEmpty) return;
         final file = files.first;
@@ -588,10 +587,8 @@ class _AnnotatorHomePageState extends State<AnnotatorHomePage> {
                   ? 'Сетка делит атлас на ${rows}×${cols} тайлов'
                   : '⚠️ Размер не делит атлас без остатка (${_atlasImage!.width}×${_atlasImage!.height})',
         ),
-        onSubmitted: (v) {
-          // Size locked during runtime: keep helper text refresh only
-          setState(() {});
-          // setState(() => _tileSize = n); // disabled
+        onChanged: (v) {
+          _tileSize = int.tryParse(v) ?? 0;
         },
       ),
     );