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>

backend/internal/infra/server/server.go

@@ -92,6 +92,7 @@ func NewRouter(
 
 		r.Route("/dishes", func(r chi.Router) {
 			r.Get("/", dishHandler.List)
+			r.Get("/search", dishHandler.Search)
 			r.Get("/{id}", dishHandler.GetByID)
 		})
 
@@ -111,6 +112,7 @@ func NewRouter(
 
 		r.Route("/diary", func(r chi.Router) {
 			r.Get("/", diaryHandler.GetByDate)
+			r.Get("/recent", diaryHandler.GetRecent)
 			r.Post("/", diaryHandler.Create)
 			r.Delete("/{id}", diaryHandler.Delete)
 		})