feat: mount CartSnackbar in AppProviders

client/src/app/providers/AppProviders.tsx

@@ -3,6 +3,7 @@ import CssBaseline from '@mui/material/CssBaseline'
 import { ThemeProvider, createTheme } from '@mui/material/styles'
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
 import { ThemeControllerProvider, useThemeController } from '@/app/providers/theme-controller'
+import { CartSnackbar } from '@/shared/ui/CartSnackbar'
 import { SseProvider } from './SseProvider'
 
 function AppThemeInner({ children }: PropsWithChildren) {
@@ -187,6 +188,7 @@ export function AppProviders({ children }: PropsWithChildren) {
   return (
     <QueryClientProvider client={queryClient}>
       <SseProvider />
+      <CartSnackbar />
       <ThemeControllerProvider>
         <AppThemeInner>{children}</AppThemeInner>
       </ThemeControllerProvider>