1.6.0 #9: auto-backup programado a iCloud Drive/Archivos

El BackupService (export JSON v3 lossless a local + iCloud ubiquity, retención,
restore, premium-gated) ya existía de 1.1.0 pero solo era manual. Añadido lo automático:
- BackupService.runScheduledBackupIfNeeded() (config vía UserDefaults, gate por
  backupsEnabled+premium, respeta frecuencia).
- Disparo en foreground (scenePhase .active) en background queue.
- Frecuencia Off/Diario/Semanal/Mensual + fecha del último backup en Settings
  (SettingsViewModel.autoBackupFrequencyDays + updateAutoBackupFrequency).
- Strings en 7 idiomas.

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

PortfolioJournal/Services/BackupService.swift

@@ -85,6 +85,30 @@ class BackupService {
         return records.sorted { $0.date > $1.date }
     }
 
+    /// Runs an automatic backup if auto-backup is enabled and the configured
+    /// interval has elapsed since the last one. Call on app foreground. Reads its
+    /// config from UserDefaults so it needs no coupling to the Settings VM. The
+    /// backup content is the lossless JSON v3 export (goals, contributions, journal).
+    @discardableResult
+    func runScheduledBackupIfNeeded() -> Bool {
+        let d = UserDefaults.standard
+        // `backupsEnabled` is only settable by Premium users, so it also gates this.
+        guard d.bool(forKey: "backupsEnabled") else { return false }
+        let frequencyDays = d.integer(forKey: "autoBackupFrequencyDays")   // 0 = off
+        guard frequencyDays > 0 else { return false }
+
+        if let last = d.object(forKey: "lastAutoBackupDate") as? Date,
+           dateProvider().timeIntervalSince(last) < Double(frequencyDays) * 86_400 {
+            return false
+        }
+
+        let retention = (d.object(forKey: "backupRetentionCount") as? Int) ?? 10
+        let includeICloud = d.bool(forKey: "cloudSyncEnabled")
+        _ = createBackup(retentionCount: retention, includeICloud: includeICloud)
+        d.set(dateProvider(), forKey: "lastAutoBackupDate")
+        return true
+    }
+
     func listAllBackups(includeICloud: Bool) -> [BackupRecord] {
         var records: [BackupRecord] = []
         if let localDir = backupDirectory() {