Add 12 cohesive app themes with matching subscription and lock screens

- Create AppTheme enum bundling color tint, icon pack, entry style, voting layout, paywall style, and lock screen style into unified themes
- Add AppThemePickerView for selecting themes with preview cards and detail sheets
- Extend PaywallStyle to 12 variants (celestial, garden, neon, minimal, zen, editorial, mixtape, heartfelt, luxe, forecast, playful, journal)
- Add LockScreenStyle enum with 13 variants including aurora default
- Create themed subscription paywalls with unique backgrounds, decorative elements, and typography for each style
- Create themed lock screens with unique backgrounds, central elements, and unlock buttons
- Update FeelsSubscriptionStoreView to read style from AppStorage so it auto-matches current theme
- Update PaywallPreviewSettingsView to support all 12 paywall styles

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Shared/Views/CustomizeView/CustomizeView.swift

@@ -15,6 +15,8 @@ struct CustomizeContentView: View {
 
     @AppStorage(UserDefaultsStore.Keys.theme.rawValue, store: GroupUserDefaults.groupDefaults) private var theme: Theme = .system
 
+    @State private var showThemePicker = false
+
     var body: some View {
         ScrollView {
             VStack(spacing: 24) {
@@ -22,6 +24,50 @@ struct CustomizeContentView: View {
                 TipView(CustomizeLayoutTip())
                     .tipBackground(Color(.secondarySystemBackground))
 
+                // QUICK THEMES
+                SettingsSection(title: "Quick Start") {
+                    Button(action: { showThemePicker = true }) {
+                        HStack(spacing: 16) {
+                            // Emoji preview
+                            ZStack {
+                                LinearGradient(
+                                    colors: [.purple.opacity(0.8), .blue.opacity(0.8), .cyan.opacity(0.8)],
+                                    startPoint: .topLeading,
+                                    endPoint: .bottomTrailing
+                                )
+                                Text("🎨")
+                                    .font(.title)
+                            }
+                            .frame(width: 56, height: 56)
+                            .clipShape(RoundedRectangle(cornerRadius: 12))
+
+                            VStack(alignment: .leading, spacing: 4) {
+                                Text("Browse Themes")
+                                    .font(.headline)
+                                    .foregroundColor(.primary)
+
+                                Text("12 curated combinations of colors, icons, and layouts")
+                                    .font(.caption)
+                                    .foregroundColor(.secondary)
+                                    .lineLimit(2)
+                            }
+
+                            Spacer()
+
+                            Image(systemName: "chevron.right")
+                                .font(.subheadline.weight(.semibold))
+                                .foregroundColor(.secondary)
+                        }
+                        .padding(12)
+                        .background(colorScheme == .dark ? Color(.systemGray6) : .white)
+                        .clipShape(RoundedRectangle(cornerRadius: 16))
+                    }
+                    .buttonStyle(.plain)
+                }
+                .sheet(isPresented: $showThemePicker) {
+                    AppThemePickerView()
+                }
+
                 // APPEARANCE
                 SettingsSection(title: "Appearance") {
                     VStack(spacing: 16) {