## Summary
- Add a new **Chart color scheme** dropdown in Settings > Appearance
allowing users to choose between 4 color palettes: **Colorful** (new
default), **Neutral** (previous zinc grayscale), **Blue**, and **Pink**
- Persist the setting in a new `user_settings` table with instant
client-side feedback via localStorage + cookie
- All charts across dashboard, categories, budgets, and cashflow update
instantly when switching schemes
- Reduced colorful palette intensity (shifted from 500/600 to 300/400
range) for lower contrast