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/domain/diary/handler.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"log/slog"
 	"net/http"
+	"strconv"
 
 	"github.com/food-ai/backend/internal/infra/middleware"
 	"github.com/go-chi/chi/v5"
@@ -15,6 +16,7 @@ type DiaryRepository interface {
 	ListByDate(ctx context.Context, userID, date string) ([]*Entry, error)
 	Create(ctx context.Context, userID string, req CreateRequest) (*Entry, error)
 	Delete(ctx context.Context, id, userID string) error
+	GetRecent(ctx context.Context, userID string, limit int) ([]*RecentDiaryItem, error)
 }
 
 // DishRepository is the subset of dish.Repository used by Handler to resolve dish IDs.
@@ -119,6 +121,31 @@ func (h *Handler) Create(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusCreated, entry)
 }
 
+// GetRecent handles GET /diary/recent?limit=<n>
+func (h *Handler) GetRecent(w http.ResponseWriter, r *http.Request) {
+	userID := middleware.UserIDFromCtx(r.Context())
+	if userID == "" {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	limit := 10
+	if limitStr := r.URL.Query().Get("limit"); limitStr != "" {
+		if parsed, parseError := strconv.Atoi(limitStr); parseError == nil && parsed > 0 && parsed <= 20 {
+			limit = parsed
+		}
+	}
+	items, queryError := h.repo.GetRecent(r.Context(), userID, limit)
+	if queryError != nil {
+		slog.Error("get recent diary items", "err", queryError)
+		writeError(w, http.StatusInternalServerError, "failed to get recent items")
+		return
+	}
+	if items == nil {
+		items = []*RecentDiaryItem{}
+	}
+	writeJSON(w, http.StatusOK, items)
+}
+
 // Delete handles DELETE /diary/{id}
 func (h *Handler) Delete(w http.ResponseWriter, r *http.Request) {
 	userID := middleware.UserIDFromCtx(r.Context())