feat: UI color theming system with live preview, presets and server sync

- RGBA color picker with live preview (debounce 50ms)
- 30 preset colors + 12 theme presets (Ocean, Forest, Sunset, Royal, etc.)
- Header image selection from configurable image library
- Export/Import theme as JSON via clipboard
- CSS variable theming across all UI elements: NitroCard headers/tabs,
  context menus, buttons (primary/dark/gray), InfoStand, toolbar,
  room tools, purse, progress bars, sliders
- All elements use var(--name, fallback) for zero visual change when default
- Smooth 0.3s CSS transitions on theme change
- Server-side persistence via WebSocket (packets 10047/10048)
- Integrated Color/Image tabs into BackgroundsView panel
- All strings use LocalizeText() for i18n support
- Settings persisted in localStorage + server sync with 1s debounce
- Added react-colorful dependency

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