feat: food search sheet with FTS+trgm, dish/recent endpoints, multilingual aliases

Backend:
- GET /dishes/search — hybrid FTS (english + simple) + trgm + ILIKE search
- GET /diary/recent — recently used dishes and products for the current user
- product search upgraded: FTS on canonical_name and product_aliases, ranked by GREATEST(ts_rank, similarity)
- importoff: collect product_name_ru/de/fr/... as product_aliases for multilingual search (e.g. "сникерс" → "Snickers")
- migrations: FTS + trgm indexes merged into 001_initial_schema.sql (002 removed)

Flutter:
- FoodSearchSheet: debounced search field, recently-used section, product/dish results, scan-photo and barcode chips
- DishPortionSheet: quick ½/1/1½/2 buttons + custom input
- + button in meal card now opens FoodSearchSheet instead of going directly to AI scan
- 7 new l10n keys across all 12 languages

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

client/lib/l10n/app_localizations_ja.dart

@@ -321,4 +321,30 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get perHundredG => '100gあたり';
+
+  @override
+  String get searchFoodHint => '食品と料理を検索...';
+
+  @override
+  String get recentlyUsedLabel => '最近使用';
+
+  @override
+  String get productsSection => '食品';
+
+  @override
+  String get dishesSection => '料理';
+
+  @override
+  String noResultsForQuery(String query) {
+    return '「$query」の検索結果はありません';
+  }
+
+  @override
+  String get servingsLabel => '人前';
+
+  @override
+  String get addToDiary => '日記に追加';
+
+  @override
+  String get scanDishPhoto => '写真をスキャン';
 }