feat: show dish recognition result as bottom sheet on home screen

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>

client/lib/features/scan/recognition_service.dart

@@ -1,8 +1,10 @@
 import 'dart:convert';
 
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:image_picker/image_picker.dart';
 
 import '../../core/api/api_client.dart';
+import '../../core/auth/auth_provider.dart';
 
 // ---------------------------------------------------------------------------
 // Models
@@ -181,3 +183,7 @@ class RecognitionService {
     return {'image_base64': base64Data, 'mime_type': mimeType};
   }
 }
+
+final recognitionServiceProvider = Provider<RecognitionService>((ref) {
+  return RecognitionService(ref.read(apiClientProvider));
+});