platos: segundo plato por comida (ensalada + salmon)

- MealSlot.secondaryDishId (opcional, aditivo CloudKit); se limpia al
  sustituir/quitar/vaciar/marcar comer fuera y viaja en swaps, copia de
  semana anterior, undo y snapshot KV de iCloud (retrocompatible)
- Picker de hueco lleno: toggle "anadir como segundo plato" + boton para
  quitarlo; HomeViewModel.assignSecondaryDish/removeSecondaryDish
- Se muestra "Plato + Segundo" en calendario, widget y export; la lista
  de la compra incluye los ingredientes del segundo; stats lo cuentan
- Evento analytics secondary_dish_added; strings en 6 idiomas

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013H6bXqGX1ygwib1Dm3n3UG

MealMood/Views/Home/WeekCalendarView.swift

@@ -214,6 +214,7 @@ struct WeekCalendarView: View {
             dayOfWeek: day,
             mealType: mealType.rawValue,
             dishId: preferred.dishId,
+            secondaryDishId: preferred.secondaryDishId,
             isRuleOverridden: preferred.isRuleOverridden,
             isEatingOut: preferred.isEatingOut
         )
@@ -264,8 +265,9 @@ struct WeekCalendarView: View {
         if let slot = slot, let dishId = slot.dishId,
            let dishData = dishData(for: dishId) {
             let dishTags = tags.filter { dishData.tagIds.contains($0.id) }
+            let secondaryName = slot.secondaryDishId.flatMap { self.dishData(for: $0)?.name }
             FilledSlotView(
-                dishName: dishData.name,
+                dishName: secondaryName.map { "\(dishData.name) + \($0)" } ?? dishData.name,
                 dishDescription: dishData.descriptionText,
                 tags: dishTags.map { (name: $0.localizedName(language: settings.languageEnum.resolved()), color: $0.color) },
                 mealType: mealType,
@@ -321,6 +323,7 @@ struct WeekCalendarView: View {
         let dayOfWeek: Int
         let mealType: String
         let dishId: UUID?
+        let secondaryDishId: UUID?
         let isRuleOverridden: Bool
         let isEatingOut: Bool
     }
@@ -370,6 +373,7 @@ struct WeekCalendarView: View {
                 dayOfWeek: preferred.dayOfWeek,
                 mealType: preferred.mealType,
                 dishId: preferred.dishId,
+                secondaryDishId: preferred.secondaryDishId,
                 isRuleOverridden: preferred.isRuleOverridden,
                 isEatingOut: preferred.isEatingOut
             )