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/dish/handler.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"log/slog"
 	"net/http"
+	"strconv"
 
 	"github.com/go-chi/chi/v5"
 )
@@ -18,6 +19,31 @@ func NewHandler(repo *Repository) *Handler {
 	return &Handler{repo: repo}
 }
 
+// Search handles GET /dishes/search?q=<query>&limit=<n>
+func (h *Handler) Search(w http.ResponseWriter, r *http.Request) {
+	query := r.URL.Query().Get("q")
+	if query == "" {
+		writeJSON(w, http.StatusOK, []*DishSearchResult{})
+		return
+	}
+	limit := 10
+	if limitStr := r.URL.Query().Get("limit"); limitStr != "" {
+		if parsed, parseError := strconv.Atoi(limitStr); parseError == nil && parsed > 0 && parsed <= 50 {
+			limit = parsed
+		}
+	}
+	results, searchError := h.repo.Search(r.Context(), query, limit)
+	if searchError != nil {
+		slog.Error("search dishes", "err", searchError)
+		writeError(w, http.StatusInternalServerError, "failed to search dishes")
+		return
+	}
+	if results == nil {
+		results = []*DishSearchResult{}
+	}
+	writeJSON(w, http.StatusOK, results)
+}
+
 // List handles GET /dishes — returns all dishes (no recipe variants).
 func (h *Handler) List(w http.ResponseWriter, r *http.Request) {
 	dishes, err := h.repo.List(r.Context())