Fix SwiftData migration crash on schema upgrades

Add = false/true defaults to all non-optional Bool properties so
SwiftData's lightweight migration knows what value to assign existing
rows. Replace try! ModelContainer with crash-safe do-catch that resets
the store on migration failure instead of crashing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

MealMood/Models/Dish.swift

@@ -8,7 +8,7 @@ final class Dish {
     var descriptionText: String?
     var tagIds: [UUID]
     var createdAt: Date
-    var isPriority: Bool
+    var isPriority: Bool = false
 
     init(
         id: UUID = UUID(),