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/toolbar/ToolbarView.tsx

@@ -69,7 +69,7 @@ export const ToolbarView: FC<{ isInRoom: boolean }> = props =>
 					<ToolbarMeView setMeExpanded={ setMeExpanded } unseenAchievementCount={ getTotalUnseen } useGuideTool={ useGuideTool } />
 				</motion.div> )}
 			</AnimatePresence>
-            <Flex alignItems="center" className="absolute bottom-0 left-0 w-full h-[55px] bg-[rgba(28,28,32,.95)] [box-shadow:inset_0_5px_#22222799,inset_0_-4px_#12121599] py-1 px-3" gap={ 2 }>
+            <Flex alignItems="center" className="absolute bottom-0 left-0 w-full h-[55px] [box-shadow:inset_0_5px_#22222799,inset_0_-4px_#12121599] py-1 px-3" gap={ 2 } style={ { backgroundColor: 'var(--ui-dark-bg, rgba(28,28,32,.95))' } }>
                 <Flex alignItems="center" gap={ 2 } className="flex-shrink-0">
                     <Flex center pointer className={ 'relative w-[50px] h-[45px] overflow-hidden ' + (isMeExpanded ? 'active ' : '') } onClick={ event =>
                     {