fix: fix menu generation errors and show planned meals on home screen

Backend fixes:
- migration 003: add 'menu' value to recipe_source enum (was causing SQLSTATE 22P02)
- migration 004: rename recipe_products→recipe_ingredients, product_id→ingredient_id (was causing SQLSTATE 42P01)
- dish/repository.go: fix INSERT INTO tags using $1/$1 for two columns → $1/$2 (was causing SQLSTATE 42P08)
- home/handler.go: replace non-existent saved_recipes table with correct joins (recipes→dishes→dish_translations, user_saved_recipes) so today's plan and recommendations load correctly
- reqlog: new slog.Handler wrapper that adds request_id and stack trace to ERROR-level logs
- all handlers: slog.Error→slog.ErrorContext so error logs include request context; writeError includes request_id in response body

Client:
- home_screen.dart: extend home screen to future dates, show planned meals as ghost entries
- l10n: add new localisation keys for home screen date navigation and planned meal UI

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

backend/internal/domain/product/handler.go

@@ -8,6 +8,7 @@ import (
 	"strconv"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/food-ai/backend/internal/infra/middleware"
 )
 
 // ProductSearcher is the data layer interface used by Handler for search.
@@ -51,7 +52,7 @@ func (handler *Handler) Search(responseWriter http.ResponseWriter, request *http
 
 	products, searchError := handler.repo.Search(request.Context(), query, limit)
 	if searchError != nil {
-		slog.Error("search catalog products", "q", query, "err", searchError)
+		slog.ErrorContext(request.Context(), "search catalog products", "q", query, "err", searchError)
 		responseWriter.Header().Set("Content-Type", "application/json")
 		responseWriter.WriteHeader(http.StatusInternalServerError)
 		_, _ = responseWriter.Write([]byte(`{"error":"search failed"}`))
@@ -71,15 +72,15 @@ func (handler *Handler) Search(responseWriter http.ResponseWriter, request *http
 func (handler *Handler) GetByBarcode(responseWriter http.ResponseWriter, request *http.Request) {
 	barcode := chi.URLParam(request, "barcode")
 	if barcode == "" {
-		writeErrorJSON(responseWriter, http.StatusBadRequest, "barcode is required")
+		writeErrorJSON(responseWriter, request, http.StatusBadRequest, "barcode is required")
 		return
 	}
 
 	// Check the local catalog first.
 	catalogProduct, lookupError := handler.repo.GetByBarcode(request.Context(), barcode)
 	if lookupError != nil {
-		slog.Error("lookup product by barcode", "barcode", barcode, "err", lookupError)
-		writeErrorJSON(responseWriter, http.StatusInternalServerError, "lookup failed")
+		slog.ErrorContext(request.Context(), "lookup product by barcode", "barcode", barcode, "err", lookupError)
+		writeErrorJSON(responseWriter, request, http.StatusInternalServerError, "lookup failed")
 		return
 	}
 	if catalogProduct != nil {
@@ -90,15 +91,15 @@ func (handler *Handler) GetByBarcode(responseWriter http.ResponseWriter, request
 	// Not in catalog — fetch from Open Food Facts.
 	fetchedProduct, fetchError := handler.openFoodFacts.Fetch(request.Context(), barcode)
 	if fetchError != nil {
-		slog.Warn("open food facts fetch failed", "barcode", barcode, "err", fetchError)
-		writeErrorJSON(responseWriter, http.StatusNotFound, "product not found")
+		slog.WarnContext(request.Context(), "open food facts fetch failed", "barcode", barcode, "err", fetchError)
+		writeErrorJSON(responseWriter, request, http.StatusNotFound, "product not found")
 		return
 	}
 
 	// Persist the fetched product so subsequent lookups are served from the DB.
 	savedProduct, upsertError := handler.repo.UpsertByBarcode(request.Context(), fetchedProduct)
 	if upsertError != nil {
-		slog.Warn("upsert product from open food facts", "barcode", barcode, "err", upsertError)
+		slog.WarnContext(request.Context(), "upsert product from open food facts", "barcode", barcode, "err", upsertError)
 		// Return the fetched data even if we could not cache it.
 		writeJSON(responseWriter, http.StatusOK, fetchedProduct)
 		return
@@ -107,13 +108,17 @@ func (handler *Handler) GetByBarcode(responseWriter http.ResponseWriter, request
 }
 
 type errorResponse struct {
-	Error string `json:"error"`
+	Error     string `json:"error"`
+	RequestID string `json:"request_id,omitempty"`
 }
 
-func writeErrorJSON(responseWriter http.ResponseWriter, status int, msg string) {
+func writeErrorJSON(responseWriter http.ResponseWriter, request *http.Request, status int, msg string) {
 	responseWriter.Header().Set("Content-Type", "application/json")
 	responseWriter.WriteHeader(status)
-	_ = json.NewEncoder(responseWriter).Encode(errorResponse{Error: msg})
+	_ = json.NewEncoder(responseWriter).Encode(errorResponse{
+		Error:     msg,
+		RequestID: middleware.RequestIDFromCtx(request.Context()),
+	})
 }
 
 func writeJSON(responseWriter http.ResponseWriter, status int, value any) {