Update Neon colors and show color circles in theme picker

- Update NeonMoodTint to use synthwave colors matching Neon voting style
  (cyan, lime, yellow, orange, magenta)
- Replace text label with 5 color circles in theme preview Colors row
- Remove unused textColor customization code and picker views
- Add .id(moodTint) to Month/Year views for color refresh
- Clean up various unused color-related code

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

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

Shared/Onboarding/views/OnboardingCustomizeTwo.swift

@@ -47,24 +47,6 @@ struct OnboardingCustomizeTwo: View {
                                 .fixedSize(horizontal: false, vertical: true)
                                 .foregroundColor(.white)
                             ImagePackPickerView()
-                            
-                            Text(String(localized: "onboarding_title_customize_two_section_two_title"))
-                                .font(.title3)
-                                .padding()
-                                .fixedSize(horizontal: false, vertical: true)
-                                .foregroundColor(.white)
-                            
-                            
-                            TintPickerView()
-                            
-                            Text(String(localized: "onboarding_title_customize_two_section_three_title"))
-                                .font(.title3)
-                                .padding()
-                                .fixedSize(horizontal: false, vertical: true)
-                                .foregroundColor(.white)
-                            
-                            
-                            TextColorPickerView()
                         }
                     }
                 }