fix(receipt-import): show explicit validation errors on create-and-select

flutter/lib/features/import/presentation/receipt_import_tab.dart

@@ -354,21 +354,39 @@ class _EditDialogState extends State<_EditDialog> {
   }
 
   bool get _canConfirm {
-    if (_entryMode == _ProductEntryMode.create) {
-      return !_isCreatingProduct &&
-          _newProductNameCtrl.text.trim().isNotEmpty &&
-          _newCategoryId != null;
-    }
+    if (_isCreatingProduct) return false;
+    if (_entryMode == _ProductEntryMode.create) return true;
     return _productId != null;
   }
 
   Future<void> _confirm() async {
     if (_entryMode == _ProductEntryMode.create) {
-      if (widget.onCreate == null || _newCategoryId == null) return;
+      final trimmedName = _newProductNameCtrl.text.trim();
+      if (trimmedName.isEmpty) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('Ange ett produktnamn först.')),
+        );
+        return;
+      }
+
+      if (_newCategoryId == null) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('Välj kategori innan du skapar produkten.')),
+        );
+        return;
+      }
+
+      if (widget.onCreate == null) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('Produktskapande är inte tillgängligt i den här vyn.')),
+        );
+        return;
+      }
+
       setState(() => _isCreatingProduct = true);
       try {
         final newProduct = await widget.onCreate!(
-          _newProductNameCtrl.text.trim(),
+          trimmedName,
           _newCategoryId!,
         );
         if (newProduct == null || !mounted) {