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/recognition/sse.go

@@ -147,17 +147,17 @@ func (broker *SSEBroker) ServeSSE(responseWriter http.ResponseWriter, request *h
 
 	job, fetchError := broker.jobRepo.GetJobByID(request.Context(), jobID)
 	if fetchError != nil {
-		writeErrorJSON(responseWriter, http.StatusNotFound, "job not found")
+		writeErrorJSON(responseWriter, request, http.StatusNotFound, "job not found")
 		return
 	}
 	if job.UserID != userID {
-		writeErrorJSON(responseWriter, http.StatusForbidden, "forbidden")
+		writeErrorJSON(responseWriter, request, http.StatusForbidden, "forbidden")
 		return
 	}
 
 	flusher, supported := responseWriter.(http.Flusher)
 	if !supported {
-		writeErrorJSON(responseWriter, http.StatusInternalServerError, "streaming not supported")
+		writeErrorJSON(responseWriter, request, http.StatusInternalServerError, "streaming not supported")
 		return
 	}