Canteen Management

Add a 'Used in' column to Recipes & costing, matching the prototype column of the same name, showing todays real count per meal slot for each recipe -- never a forecast.

Patient-tray recipes: ProductionPlanLine.PatientPortions for todays service date (already live from active diet orders).
Counter-sold recipes: todays completed sales, bucketed by Sale.ConsumptionMealSlotId -- the same slot ProductionConsumptionPoster already resolves and snapshots on every sale completion (used for the cook sheets own Served so far column). No new slot-classification logic was needed.

Backend: RecipeDto.UsedInToday (new RecipeUsageDto { Label, Count }), computed in RecipeService from ProductionPlanLine + Sale/SaleLine, no new endpoint or permission (rides on canteen.recipes.read). Frontend: new column on the Recipes & costing table.