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/l10n/app_localizations_ko.dart

@@ -538,4 +538,37 @@ class AppLocalizationsKo extends AppLocalizations {
 
   @override
   String get productAddedToShelf => '저장실에 추가되었습니다';
+
+  @override
+  String recognitionFoundProducts(int count) {
+    return '$count개 제품 찾음';
+  }
+
+  @override
+  String get recognitionAddAll => '모두 추가';
+
+  @override
+  String get recognitionAddToStock => '저장실에 추가';
+
+  @override
+  String recognitionAdded(int count) {
+    return '$count개 제품 추가됨';
+  }
+
+  @override
+  String get recognitionProductsFailed => '제품 추가 실패';
+
+  @override
+  String get recognitionEmpty => '제품을 찾을 수 없습니다';
+
+  @override
+  String recognitionConfidence(int percent) {
+    return '$percent% 신뢰도';
+  }
+
+  @override
+  String get recognitionReplaceProduct => '제품 교체';
+
+  @override
+  String get scanJobCloseHint => '앱을 닫아도 됩니다 — 이 스캔은 제품 화면의 최근 스캔에 표시됩니다';
 }