Add UI Customization Panel with full color theming

- New "Interfaccia" panel with color picker (HSV + hex/RGB/alpha + 30 presets)
- Profile background customization tab
- Accent color propagates via CSS variables to: card headers/tabs,
  context menus, Button dark/primary/gray variants, InfoStand panels,
  toolbar, room tools, purse, .btn-primary/.btn-dark CSS classes
- All elements use var(--name, fallback) for zero visual change when default
- Settings persisted in localStorage
- Added react-colorful dependency
- Added ui-config.json with header images config keys

src/components/room/widgets/avatar-info/infostand/InfoStandBadgeSlotView.tsx

@@ -45,7 +45,8 @@ const BadgeMiniPicker: FC<{
     return (
         <div
             ref={ ref }
-            className="absolute right-[calc(100%+8px)] top-0 z-50 bg-[rgba(28,28,32,0.97)] border border-white/20 rounded-md p-2 shadow-lg min-w-[160px]"
+            className="absolute right-[calc(100%+8px)] top-0 z-50 border border-white/20 rounded-md p-2 shadow-lg min-w-[160px]"
+            style={ { backgroundColor: 'var(--ui-dark-bg, rgba(28,28,32,0.97))' } }
             onClick={ e => e.stopPropagation() }>
             <input
                 autoFocus