Release 1.3.0: onboarding UX, charts paywall banner, re-engagement notifications, Crashlytics

- Crashlytics: add FirebaseCrashlytics framework + dSYM upload build phase
- Onboarding: useSampleData off by default, Add First Investment as primary CTA
- AddSourceView: contextual placeholder and footer explaining what a source is
- Charts: CompactPaywallBanner visible to free users on every visit
- Notifications: re-engagement (7d) and monthly check-in local notifications
- Paywall: decorative chart preview replacing static crown icon
- Localization: all new strings in en + es-ES

PortfolioJournal/App/AppDelegate.swift

@@ -2,6 +2,7 @@ import UIKit
 import UserNotifications
 import FirebaseCore
 import FirebaseAnalytics
+import FirebaseCrashlytics
 import GoogleMobileAds
 
 class AppDelegate: NSObject, UIApplicationDelegate {

PortfolioJournal/App/PortfolioJournalApp.swift

@@ -38,6 +38,8 @@ struct PortfolioJournalApp: App {
                 // iCloud changes made on other devices while this device was inactive
                 // are reflected immediately without waiting for a remote-change notification.
                 coreDataStack.refreshFromCloudKit()
+                NotificationService.shared.scheduleReEngagementNotification()
+                NotificationService.shared.scheduleMonthlyCheckIn()
             } else if newPhase == .background {
                 guard iapService.isPremium else { return }
                 guard UserDefaults.standard.bool(forKey: "backupsEnabled") else { return }