Remove "Определить блюдо" from ScanScreen and the /scan/dish route.
The + button on each meal card now triggers dish recognition inline —
picks image, shows loading dialog, then presents DishResultSheet as a
modal bottom sheet. After adding to diary the sheet closes and the user
stays on home.
Also fix Navigator.pop crash: showDialog uses the root navigator by
default, so capture Navigator.of(context, rootNavigator: true) before
the async gap and use it to close the loading dialog.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>