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/ViewModels/HomeViewModel.swift

@@ -11,6 +11,7 @@ final class HomeViewModel: ObservableObject {
 
     private struct SlotSnapshot {
         let dishId: UUID?
+        let secondaryDishId: UUID?
         let isRuleOverridden: Bool
         let isEatingOut: Bool
     }
@@ -94,6 +95,7 @@ final class HomeViewModel: ObservableObject {
         }
 
         slot.dishId = dish.id
+        slot.secondaryDishId = nil
         slot.isRuleOverridden = isOverride
         plan.updatedAt = Date()
 
@@ -104,6 +106,25 @@ final class HomeViewModel: ObservableObject {
         showToastMessage(localizedString("toast_dish_assigned", language: settings.languageEnum.resolved()))
     }
 
+    /// Adds a companion dish to an already-filled slot ("ensalada + salmón").
+    func assignSecondaryDish(_ dish: Dish, to slot: MealSlot, plan: WeekPlan, settings: AppSettings) {
+        guard slot.dishId != nil, slot.dishId != dish.id else { return }
+        captureUndoSnapshot(plan: plan)
+        slot.secondaryDishId = dish.id
+        plan.updatedAt = Date()
+        AnalyticsService.logEvent("secondary_dish_added")
+        HapticManager.shared.notification(type: .success)
+        showToastMessage(localizedString("toast_dish_assigned", language: settings.languageEnum.resolved()))
+    }
+
+    func removeSecondaryDish(from slot: MealSlot, plan: WeekPlan) {
+        guard slot.secondaryDishId != nil else { return }
+        captureUndoSnapshot(plan: plan)
+        slot.secondaryDishId = nil
+        plan.updatedAt = Date()
+        HapticManager.shared.notification(type: .warning)
+    }
+
     func removeDish(from slot: MealSlot, plan: WeekPlan, settings: AppSettings) {
         captureUndoSnapshot(plan: plan)
 
@@ -112,6 +133,7 @@ final class HomeViewModel: ObservableObject {
             slot.calendarEventId = nil
         }
         slot.dishId = nil
+        slot.secondaryDishId = nil
         slot.isRuleOverridden = false
         plan.updatedAt = Date()
         applyCalendarSyncPolicy(plan: plan, settings: settings, shouldNotify: false)
@@ -182,6 +204,7 @@ final class HomeViewModel: ObservableObject {
                 slot.calendarEventId = nil
             }
             slot.dishId = nil
+            slot.secondaryDishId = nil
             slot.isRuleOverridden = false
             slot.isEatingOut = false
         }
@@ -247,8 +270,11 @@ final class HomeViewModel: ObservableObject {
         }
 
         let targetDishId = targetSlot.dishId
+        let targetSecondaryId = targetSlot.secondaryDishId
         sourceSlot.dishId = targetDishId
         targetSlot.dishId = sourceDishId
+        targetSlot.secondaryDishId = sourceSlot.secondaryDishId
+        sourceSlot.secondaryDishId = targetSecondaryId
         sourceSlot.isRuleOverridden = false
         targetSlot.isRuleOverridden = false
 
@@ -293,9 +319,12 @@ final class HomeViewModel: ObservableObject {
             let key = SlotKey(dayOfWeek: slot.dayOfWeek, mealType: slot.mealType)
             if let previousDishId = previousByKey[key]?.dishId, dishIds.contains(previousDishId) {
                 slot.dishId = previousDishId
+                let previousSecondary = previousByKey[key]?.secondaryDishId
+                slot.secondaryDishId = previousSecondary.flatMap { dishIds.contains($0) ? $0 : nil }
                 copiedCount += 1
             } else {
                 slot.dishId = nil
+                slot.secondaryDishId = nil
             }
             slot.isRuleOverridden = false
             updateRuleOverrideFlag(for: slot, plan: currentPlan, allTags: allTags, allDishes: allDishes)
@@ -324,10 +353,12 @@ final class HomeViewModel: ObservableObject {
 
             if let snap = lastSlotsSnapshot[slot.id] {
                 slot.dishId = snap.dishId
+                slot.secondaryDishId = snap.secondaryDishId
                 slot.isRuleOverridden = snap.isRuleOverridden
                 slot.isEatingOut = snap.isEatingOut
             } else {
                 slot.dishId = nil
+                slot.secondaryDishId = nil
                 slot.isRuleOverridden = false
                 slot.isEatingOut = false
             }
@@ -353,7 +384,7 @@ final class HomeViewModel: ObservableObject {
         guard !isApplyingUndo else { return }
         lastWeekStartSnapshot = plan.weekStartDate
         lastSlotsSnapshot = Dictionary(plan.slotList.map { slot in
-            (slot.id, SlotSnapshot(dishId: slot.dishId, isRuleOverridden: slot.isRuleOverridden, isEatingOut: slot.isEatingOut))
+            (slot.id, SlotSnapshot(dishId: slot.dishId, secondaryDishId: slot.secondaryDishId, isRuleOverridden: slot.isRuleOverridden, isEatingOut: slot.isEatingOut))
         }, uniquingKeysWith: { first, _ in first })
         hasUndoSnapshot = true
     }
@@ -463,6 +494,7 @@ final class HomeViewModel: ObservableObject {
             slot.calendarEventId = nil
         }
         slot.dishId = nil
+        slot.secondaryDishId = nil
         slot.isRuleOverridden = false
         slot.isEatingOut = true
         plan.updatedAt = Date()