feat: add admin layout with sub-navigation and routing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.tsx

@@ -4,6 +4,7 @@ import { BrowserRouter } from 'react-router-dom'
 import { ThemeProvider } from './design-system/providers/ThemeProvider'
 import { GlobalFilterProvider } from './design-system/providers/GlobalFilterProvider'
 import { CommandPaletteProvider } from './design-system/providers/CommandPaletteProvider'
+import { ToastProvider } from './design-system/composites/Toast/Toast'
 import App from './App'
 import './index.css'
 
@@ -13,7 +14,9 @@ createRoot(document.getElementById('root')!).render(
       <ThemeProvider>
         <GlobalFilterProvider>
           <CommandPaletteProvider>
-            <App />
+              <ToastProvider>
+                <App />
+              </ToastProvider>
           </CommandPaletteProvider>
         </GlobalFilterProvider>
       </ThemeProvider>