refactor(adminfront): replace sonner with custom use-toast matching devfront UX policy

adminfront/src/main.tsx

@@ -6,6 +6,7 @@ import { RouterProvider } from "react-router-dom";
 import { queryClient } from "./app/queryClient";
 import { router } from "./app/routes";
 import { oidcConfig } from "./lib/auth";
+import { Toaster } from "./components/ui/toaster";
 import "./index.css";
 
 const rootElement = document.getElementById("root");
@@ -19,6 +20,7 @@ createRoot(rootElement).render(
     <AuthProvider {...oidcConfig}>
       <QueryClientProvider client={queryClient}>
         <RouterProvider router={router} />
+        <Toaster />
       </QueryClientProvider>
     </AuthProvider>
   </StrictMode>,