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/Views/SettingsView/SettingsTabView.swift

@@ -22,7 +22,8 @@ struct SettingsTabView: View {
     @EnvironmentObject var iapManager: IAPManager
 
     @AppStorage(UserDefaultsStore.Keys.theme.rawValue, store: GroupUserDefaults.groupDefaults) private var theme: Theme = .system
-    @AppStorage(UserDefaultsStore.Keys.textColor.rawValue, store: GroupUserDefaults.groupDefaults) private var textColor: Color = DefaultTextColor.textColor
+
+    private var textColor: Color { theme.currentTheme.labelColor }
 
     var body: some View {
         VStack(spacing: 0) {
@@ -85,7 +86,9 @@ struct UpgradeBannerView: View {
     let trialExpirationDate: Date?
 
     @Environment(\.colorScheme) private var colorScheme
-    @AppStorage(UserDefaultsStore.Keys.textColor.rawValue, store: GroupUserDefaults.groupDefaults) private var textColor: Color = DefaultTextColor.textColor
+    @AppStorage(UserDefaultsStore.Keys.theme.rawValue, store: GroupUserDefaults.groupDefaults) private var theme: Theme = .system
+
+    private var textColor: Color { theme.currentTheme.labelColor }
 
     var body: some View {
         VStack(spacing: 12) {