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/Models/MoodTintable.swift

@@ -7,12 +7,6 @@
 
 import SwiftUI
 
-struct DefaultTextColor {
-    static var textColor: Color {
-        Color(UIColor.label)
-    }
-}
-
 protocol MoodTintable {
     static func color(forMood mood: Mood) -> Color
     static func secondary(forMood mood: Mood) -> Color
@@ -232,37 +226,44 @@ final class AllRedMoodTint: MoodTintable {
 }
 
 final class NeonMoodTint: MoodTintable {
+    // Synthwave color palette matching the Neon voting style
+    private static let neonCyan = Color(red: 0.0, green: 1.0, blue: 0.82)
+    private static let neonLime = Color(red: 0.2, green: 1.0, blue: 0.6)
+    private static let neonYellow = Color(red: 1.0, green: 0.9, blue: 0.0)
+    private static let neonOrange = Color(red: 1.0, green: 0.5, blue: 0.0)
+    private static let neonMagenta = Color(red: 1.0, green: 0.0, blue: 0.8)
+
     static func color(forMood mood: Mood) -> Color {
         switch mood {
         case .horrible:
-            return Color(hex: "#ff1818")
+            return neonMagenta
         case .bad:
-            return Color(hex: "#FF5F1F")
+            return neonOrange
         case .average:
-            return Color(hex: "#1F51FF")
+            return neonYellow
         case .good:
-            return Color(hex: "#FFF01F")
+            return neonLime
         case .great:
-            return Color(hex: "#39FF14")
+            return neonCyan
         case .missing:
             return Color(uiColor: UIColor.systemGray2)
         case .placeholder:
             return Color(uiColor: UIColor.systemGray2)
         }
     }
-    
+
     static func secondary(forMood mood: Mood) -> Color {
         switch mood {
         case .horrible:
-            return Color(hex: "#8b1113")
+            return neonMagenta.opacity(0.6)
         case .bad:
-            return Color(hex: "#893315")
+            return neonOrange.opacity(0.6)
         case .average:
-            return Color(hex: "#0f2a85")
+            return neonYellow.opacity(0.6)
         case .good:
-            return Color(hex: "#807a18")
+            return neonLime.opacity(0.6)
         case .great:
-            return Color(hex: "#218116")
+            return neonCyan.opacity(0.6)
         case .missing:
             return Color(uiColor: UIColor.label)
         case .placeholder: