feat: improved receipt recognition, batch product add, and scan UX

- Rewrite receipt OCR prompt: completes truncated names, preserves fat%
  and flavour attributes, extracts weight/volume from line, infers
  typical package sizes for solid goods with quantity_confidence field
- Add quantity_confidence to RecognizedItem, EnrichedItem, and
  ProductJobResultItem; propagate through item enricher and worker
- Replace per-item create loop with single POST /user-products/batch call
  from RecognitionConfirmScreen
- Rebuild RecognitionConfirmScreen: amber qty border for low
  quantity_confidence, tappable product name → catalog picker,
  sort items by confidence, full L10n (no hardcoded strings)
- Add timestamps (HH:mm / d MMM HH:mm) to recent scan chips
- Show close-app hint on ProductJobWatchScreen (queued + processing)
- Refresh recentProductJobsProvider on watch screen init so new job
  appears without a manual pull-to-refresh
- App-level WidgetsBindingObserver refreshes product and dish job lists
  on resume, fixing stale lists after background/foreground transitions
- Add 9 new L10n keys across all 12 locales

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

client/lib/app.dart

@@ -5,12 +5,39 @@ import 'package:food_ai/l10n/app_localizations.dart';
 import 'core/locale/language_provider.dart';
 import 'core/router/app_router.dart';
 import 'core/theme/app_theme.dart';
+import 'features/home/home_provider.dart';
+import 'features/products/product_job_provider.dart';
 
-class App extends ConsumerWidget {
+class App extends ConsumerStatefulWidget {
   const App({super.key});
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<App> createState() => _AppState();
+}
+
+class _AppState extends ConsumerState<App> with WidgetsBindingObserver {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addObserver(this);
+  }
+
+  @override
+  void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState lifecycleState) {
+    if (lifecycleState == AppLifecycleState.resumed) {
+      ref.read(recentProductJobsProvider.notifier).refresh();
+      ref.read(todayJobsProvider.notifier).load();
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
     final router = ref.watch(routerProvider);
     final languageCode = ref.watch(languageProvider);