Add Neon/Synthwave style and 4 paywall themes

- Add 4 distinct paywall themes (Celestial, Garden, Neon, Minimal) with
  preview/switcher in debug settings
- Add Neon voting layout with synthwave equalizer bar design
- Upgrade Neon entry style with grid background, cyan/magenta gradients,
  scanline effects, and mini equalizer visualization
- Add PaywallPreviewSettingsView for testing different paywall styles
- Use consistent synthwave color palette (cyan #00FFD0, magenta #FF00CC)

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

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

Shared/Views/CustomizeView/CustomizeView.swift

@@ -587,6 +587,27 @@ struct VotingLayoutPickerCompact: View {
                         .offset(orbitOffset(index: index, total: 5, radius: 16))
                 }
             }
+        case .neon:
+            // Equalizer bars
+            ZStack {
+                RoundedRectangle(cornerRadius: 4)
+                    .fill(Color.black)
+                    .frame(width: 36, height: 36)
+                HStack(spacing: 2) {
+                    ForEach(0..<5, id: \.self) { index in
+                        let heights: [CGFloat] = [24, 18, 14, 10, 8]
+                        RoundedRectangle(cornerRadius: 1)
+                            .fill(
+                                LinearGradient(
+                                    colors: [Color(red: 0, green: 1, blue: 0.82), Color(red: 1, green: 0, blue: 0.8)],
+                                    startPoint: .top,
+                                    endPoint: .bottom
+                                )
+                            )
+                            .frame(width: 4, height: heights[index])
+                    }
+                }
+            }
         }
     }
 

Shared/Views/CustomizeView/SubViews/VotingLayoutPickerView.swift

@@ -151,6 +151,30 @@ struct VotingLayoutPickerView: View {
                         .offset(orbitOffset(index: index, total: 5, radius: 16))
                 }
             }
+        case .neon:
+            // Equalizer bars
+            ZStack {
+                // Grid background hint
+                RoundedRectangle(cornerRadius: 4)
+                    .fill(Color.black)
+                    .frame(width: 36, height: 36)
+
+                // Equalizer bars
+                HStack(spacing: 2) {
+                    ForEach(0..<5, id: \.self) { index in
+                        let heights: [CGFloat] = [24, 18, 14, 10, 8]
+                        RoundedRectangle(cornerRadius: 1)
+                            .fill(
+                                LinearGradient(
+                                    colors: [Color(red: 0, green: 1, blue: 0.82), Color(red: 1, green: 0, blue: 0.8)],
+                                    startPoint: .top,
+                                    endPoint: .bottom
+                                )
+                            )
+                            .frame(width: 4, height: heights[index])
+                    }
+                }
+            }
         }
     }