1.6.0 foundation: dedup prevención completa + atributo isEstimated

Dedup prevención: UUIDs estables (StableID v5) asignados al default Account y a las
categorías por defecto en createDefaultAccountIfNeeded, ensureDefaultCategoriesExist,
createDefaultCategories y el reset de SettingsViewModel → CloudKit fusiona nativamente,
no más acumulación de duplicados.

isEstimated: nuevo atributo Bool opcional (default NO, syncable) en Snapshot para marcar
snapshots interpolados del auto-relleno. Requiere deploy de schema CloudKit antes del
release. Compila verde (verificado antes de que el agente de widgets empezara a editar).

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

PortfolioJournal/Models/CoreData/PortfolioJournal.xcdatamodeld/PortfolioJournal.xcdatamodel/contents

@@ -100,6 +100,7 @@
         <attribute name="createdAt" optional="YES" attributeType="Date" usesScalarValueType="NO"/>
         <attribute name="date" optional="YES" attributeType="Date" usesScalarValueType="NO"/>
         <attribute name="id" optional="YES" attributeType="UUID" usesScalarValueType="NO"/>
+        <attribute name="isEstimated" optional="YES" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
         <attribute name="notes" optional="YES" attributeType="String"/>
         <attribute name="value" optional="YES" attributeType="Decimal"/>
         <relationship name="source" optional="YES" maxCount="1" deletionRule="Nullify" destinationEntity="InvestmentSource" inverseName="snapshots" inverseEntity="InvestmentSource"/>

PortfolioJournal/Models/CoreData/Snapshot+CoreDataClass.swift

@@ -18,6 +18,10 @@ public class Snapshot: NSManagedObject, Identifiable {
     @NSManaged public var value: NSDecimalNumber?
     @NSManaged public var contribution: NSDecimalNumber?
     @NSManaged public var notes: String?
+    /// True for auto-generated (interpolated) snapshots that fill a gap between two
+    /// real snapshots. Estimated snapshots are shown with a distinct marker and can
+    /// be removed in bulk. Defaults to false (model default) for all real snapshots.
+    @NSManaged public var isEstimated: Bool
     @objc public var createdAt: Date {
         get { safeValue(forKey: "createdAt", fallback: .distantPast) }
         set { setManagedValue(newValue, forKey: "createdAt") }