Rama 1.6.0: dedup CloudKit-safe (WIP: StableID + UUIDs estables en defaults)

Funde 1.5.1 en 1.6.0. Parte 1 dedup (prevención): StableID (UUIDv5 namespace+nombre),
Account.defaultAccountStableID, Category.stableID(for:) + asignación en
createDefaultCategories. Pendiente: asignar en repos + limpieza de duplicados existentes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L2p3gUZRNWW388rWFRjiU7

PortfolioJournal/Models/CoreData/Account+CoreDataClass.swift

@@ -46,6 +46,11 @@ public class Account: NSManagedObject, Identifiable {
 
 extension Account {
     static let defaultAccountName = "Default"
+
+    /// Deterministic UUID for the auto-created "Default" account, so every device
+    /// creates it as the SAME CloudKit record instead of a per-device duplicate.
+    /// See StableID.
+    static let defaultAccountStableID = StableID.v5("account:default")
 }
 
 // MARK: - Computed Properties

PortfolioJournal/Models/CoreData/Category+CoreDataClass.swift

@@ -92,9 +92,17 @@ extension Category {
         ("ETFs", "#EC4899", "chart.bar.fill")
     ]
 
+    /// Deterministic UUID for a default category, so every device creates each
+    /// default category as the SAME CloudKit record instead of a per-device
+    /// duplicate. Only meaningful for the built-in default names. See StableID.
+    static func stableID(for name: String) -> UUID {
+        StableID.v5("category:\(name.lowercased())")
+    }
+
     static func createDefaultCategories(in context: NSManagedObjectContext) {
         for (index, categoryData) in defaultCategories.enumerated() {
             let category = Category(context: context)
+            category.id = stableID(for: categoryData.name)
             category.name = categoryData.name
             category.colorHex = categoryData.colorHex
             category.icon = categoryData.icon