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/Services/NotificationService.swift

@@ -176,6 +176,62 @@ extension Notification.Name {
     static let didResetData = Notification.Name("didResetData")
 }
 
+// MARK: - Re-engagement Notifications
+
+extension NotificationService {
+    /// Schedules a re-engagement notification 7 days from now.
+    /// Call this every time the app becomes active to reset the timer.
+    func scheduleReEngagementNotification() {
+        guard isAuthorized else { return }
+
+        center.removePendingNotificationRequests(withIdentifiers: ["re_engagement"])
+
+        let content = UNMutableNotificationContent()
+        content.title = String(localized: "reengagement_title")
+        content.body = String(localized: "reengagement_body")
+        content.sound = .default
+
+        let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 7 * 24 * 3600, repeats: false)
+        let request = UNNotificationRequest(identifier: "re_engagement", content: content, trigger: trigger)
+
+        center.add(request) { error in
+            if let error = error {
+                print("Re-engagement notification error: \(error)")
+            }
+        }
+    }
+
+    /// Schedules a monthly check-in notification on the 1st of each month at 9am.
+    /// Only schedules if not already pending.
+    func scheduleMonthlyCheckIn() {
+        guard isAuthorized else { return }
+
+        let identifier = "monthly_checkin"
+        center.getPendingNotificationRequests { [weak self] requests in
+            guard let self, !requests.contains(where: { $0.identifier == identifier }) else { return }
+
+            let content = UNMutableNotificationContent()
+            content.title = String(localized: "monthly_checkin_notification_title")
+            content.body = String(localized: "monthly_checkin_notification_body")
+            content.sound = .default
+
+            var components = DateComponents()
+            components.day = 1
+            components.hour = 9
+            components.minute = 0
+
+            let trigger = UNCalendarNotificationTrigger(dateMatching: components, repeats: true)
+            let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)
+
+            self.center.add(request) { error in
+                if let error = error {
+                    print("Monthly check-in notification error: \(error)")
+                }
+            }
+        }
+    }
+}
+
 // MARK: - Background Refresh
 
 extension NotificationService {