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/savedrecipe/handler.go

@@ -35,25 +35,25 @@ func NewHandler(repo SavedRecipeRepository) *Handler {
 func (h *Handler) Save(w http.ResponseWriter, r *http.Request) {
 	userID := middleware.UserIDFromCtx(r.Context())
 	if userID == "" {
-		writeErrorJSON(w, http.StatusUnauthorized, "unauthorized")
+		writeErrorJSON(w, r, http.StatusUnauthorized, "unauthorized")
 		return
 	}
 
 	r.Body = http.MaxBytesReader(w, r.Body, maxBodySize)
 	var req SaveRequest
 	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
-		writeErrorJSON(w, http.StatusBadRequest, "invalid request body")
+		writeErrorJSON(w, r, http.StatusBadRequest, "invalid request body")
 		return
 	}
 	if req.Title == "" && req.RecipeID == "" {
-		writeErrorJSON(w, http.StatusBadRequest, "title or recipe_id is required")
+		writeErrorJSON(w, r, http.StatusBadRequest, "title or recipe_id is required")
 		return
 	}
 
 	rec, err := h.repo.Save(r.Context(), userID, req)
 	if err != nil {
-		slog.Error("save recipe", "err", err)
-		writeErrorJSON(w, http.StatusInternalServerError, "failed to save recipe")
+		slog.ErrorContext(r.Context(), "save recipe", "err", err)
+		writeErrorJSON(w, r, http.StatusInternalServerError, "failed to save recipe")
 		return
 	}
 	writeJSON(w, http.StatusCreated, rec)
@@ -63,14 +63,14 @@ func (h *Handler) Save(w http.ResponseWriter, r *http.Request) {
 func (h *Handler) List(w http.ResponseWriter, r *http.Request) {
 	userID := middleware.UserIDFromCtx(r.Context())
 	if userID == "" {
-		writeErrorJSON(w, http.StatusUnauthorized, "unauthorized")
+		writeErrorJSON(w, r, http.StatusUnauthorized, "unauthorized")
 		return
 	}
 
 	recipes, err := h.repo.List(r.Context(), userID)
 	if err != nil {
-		slog.Error("list saved recipes", "err", err)
-		writeErrorJSON(w, http.StatusInternalServerError, "failed to list saved recipes")
+		slog.ErrorContext(r.Context(), "list saved recipes", "err", err)
+		writeErrorJSON(w, r, http.StatusInternalServerError, "failed to list saved recipes")
 		return
 	}
 	if recipes == nil {
@@ -83,19 +83,19 @@ func (h *Handler) List(w http.ResponseWriter, r *http.Request) {
 func (h *Handler) GetByID(w http.ResponseWriter, r *http.Request) {
 	userID := middleware.UserIDFromCtx(r.Context())
 	if userID == "" {
-		writeErrorJSON(w, http.StatusUnauthorized, "unauthorized")
+		writeErrorJSON(w, r, http.StatusUnauthorized, "unauthorized")
 		return
 	}
 
 	id := chi.URLParam(r, "id")
 	rec, err := h.repo.GetByID(r.Context(), userID, id)
 	if err != nil {
-		slog.Error("get saved recipe", "id", id, "err", err)
-		writeErrorJSON(w, http.StatusInternalServerError, "failed to get saved recipe")
+		slog.ErrorContext(r.Context(), "get saved recipe", "id", id, "err", err)
+		writeErrorJSON(w, r, http.StatusInternalServerError, "failed to get saved recipe")
 		return
 	}
 	if rec == nil {
-		writeErrorJSON(w, http.StatusNotFound, "recipe not found")
+		writeErrorJSON(w, r, http.StatusNotFound, "recipe not found")
 		return
 	}
 	writeJSON(w, http.StatusOK, rec)
@@ -105,32 +105,36 @@ func (h *Handler) GetByID(w http.ResponseWriter, r *http.Request) {
 func (h *Handler) Delete(w http.ResponseWriter, r *http.Request) {
 	userID := middleware.UserIDFromCtx(r.Context())
 	if userID == "" {
-		writeErrorJSON(w, http.StatusUnauthorized, "unauthorized")
+		writeErrorJSON(w, r, http.StatusUnauthorized, "unauthorized")
 		return
 	}
 
 	id := chi.URLParam(r, "id")
 	if err := h.repo.Delete(r.Context(), userID, id); err != nil {
 		if errors.Is(err, ErrNotFound) {
-			writeErrorJSON(w, http.StatusNotFound, "recipe not found")
+			writeErrorJSON(w, r, http.StatusNotFound, "recipe not found")
 			return
 		}
-		slog.Error("delete saved recipe", "id", id, "err", err)
-		writeErrorJSON(w, http.StatusInternalServerError, "failed to delete recipe")
+		slog.ErrorContext(r.Context(), "delete saved recipe", "id", id, "err", err)
+		writeErrorJSON(w, r, http.StatusInternalServerError, "failed to delete recipe")
 		return
 	}
 	w.WriteHeader(http.StatusNoContent)
 }
 
 type errorResponse struct {
-	Error string `json:"error"`
+	Error     string `json:"error"`
+	RequestID string `json:"request_id,omitempty"`
 }
 
-func writeErrorJSON(w http.ResponseWriter, status int, msg string) {
+func writeErrorJSON(w http.ResponseWriter, r *http.Request, status int, msg string) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)
-	if err := json.NewEncoder(w).Encode(errorResponse{Error: msg}); err != nil {
-		slog.Error("write error response", "err", err)
+	if encodeErr := json.NewEncoder(w).Encode(errorResponse{
+		Error:     msg,
+		RequestID: middleware.RequestIDFromCtx(r.Context()),
+	}); encodeErr != nil {
+		slog.ErrorContext(r.Context(), "write error response", "err", encodeErr)
 	}
 }