1.6.0: auto-rellenar huecos (snapshots estimados) + widgets/lock screen enriquecidos

Auto-relleno (#5): SnapshotRepository.autoFillGap crea snapshots interpolados
linealmente entre los dos snapshots que bordean el hueco, marcados isEstimated.
deleteEstimatedSnapshots para borrado en bloque. Botón 'Autocompletar N meses'
(wand.and.stars) en DataGapsSheet + 'Añadir manualmente'. Idempotente. Strings 7 idiomas.

Widgets/Lock Screen (#8, vía agente): familias enriquecidas — systemSmall/Medium/Large
con net worth + cambio desde check-in + racha + próximo check-in + progreso de objetivo;
lock screen accessoryCircular (gauge objetivo/milestone), accessoryRectangular, accessoryInline.
Deep link quickupdate preservado. Solo InvestmentWidget.swift.

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

PortfolioJournal/Repositories/SnapshotRepository.swift

@@ -123,6 +123,56 @@ class SnapshotRepository: ObservableObject {
         return snapshot
     }
 
+    // MARK: - Gap Auto-Fill (estimated snapshots)
+
+    /// Creates ESTIMATED snapshots for the missing months of an internal gap,
+    /// linearly interpolated between the source's value at `from` and at `to`.
+    /// They are marked `isEstimated` so they read as clearly distinct from real
+    /// data and can be removed in bulk. Idempotent (skips months that already have
+    /// a snapshot). Returns how many were created.
+    @discardableResult
+    func autoFillGap(source: InvestmentSource, from: Date, to: Date, missingMonthDates: [Date]) -> Int {
+        let snaps = source.snapshotsArray
+        func value(atMonth month: Date) -> Decimal? {
+            snaps.filter { $0.date.startOfMonth == month.startOfMonth }
+                 .max(by: { $0.date < $1.date })?.decimalValue
+        }
+        guard let v0 = value(atMonth: from),
+              let v1 = value(atMonth: to),
+              !missingMonthDates.isEmpty else { return 0 }
+
+        let steps = missingMonthDates.count + 1   // segments between v0 and v1
+        var created = 0
+        for (i, month) in missingMonthDates.enumerated() {
+            let monthStart = month.startOfMonth
+            if snaps.contains(where: { $0.date.startOfMonth == monthStart }) { continue }
+            let fraction = Decimal(i + 1) / Decimal(steps)
+            let interpolated = v0 + (v1 - v0) * fraction
+            let snapshot = Snapshot(context: context)
+            snapshot.source = source
+            snapshot.date = monthStart
+            snapshot.value = NSDecimalNumber(decimal: interpolated)
+            snapshot.isEstimated = true
+            snapshot.notes = String(localized: "gaps_estimated_note")
+            created += 1
+        }
+        if created > 0 { save() }
+        return created
+    }
+
+    /// Deletes all estimated (auto-filled) snapshots, optionally scoped to one
+    /// source. Returns how many were removed.
+    @discardableResult
+    func deleteEstimatedSnapshots(for source: InvestmentSource? = nil) -> Int {
+        let request = NSFetchRequest<Snapshot>(entityName: "Snapshot")
+        request.predicate = NSPredicate(format: "isEstimated == YES")
+        guard let estimated = try? context.fetch(request) else { return 0 }
+        let targets = source == nil ? estimated : estimated.filter { $0.source?.id == source?.id }
+        for snapshot in targets { context.delete(snapshot) }
+        if !targets.isEmpty { save() }
+        return targets.count
+    }
+
     // MARK: - Update
 
     func updateSnapshot(