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/DayView/DayViewViewModel.swift

@@ -37,9 +37,8 @@ class DayViewViewModel: ObservableObject {
 
         DataController.shared.addNewDataListener { [weak self] in
             guard let self = self else { return }
-            withAnimation {
-                self.updateData()
-            }
+            // Avoid withAnimation for bulk data updates - it causes expensive view diffing
+            self.updateData()
         }
         updateData()
     }