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/Views/Charts/ChartsContainerView.swift

@@ -22,6 +22,14 @@ struct ChartsContainerView: View {
                         // Chart Type Selector
                         chartTypeSelector
 
+                        // Paywall nudge for free users
+                        if !viewModel.isPremium {
+                            CompactPaywallBanner(showingPaywall: $viewModel.showingPaywall)
+                                .onAppear {
+                                    FirebaseService.shared.logPaywallShown(trigger: "charts_banner")
+                                }
+                        }
+
                         // Unified Filters
                         filtersSection