[rewrite] Added shadcn ui to frontend and slightly tweaked backend

frontend/src/routes/__root.tsx

@@ -0,0 +1,28 @@
+import { QueryClient } from '@tanstack/react-query'
+import { createRootRouteWithContext, Outlet } from '@tanstack/react-router'
+import { ReactQueryDevtools } from '@tanstack/react-query-devtools'
+import { TanStackRouterDevtools } from '@tanstack/router-devtools'
+import { Toaster } from '@/components/ui/toaster'
+import GeneralError from '@/features/errors/general-error'
+import NotFoundError from '@/features/errors/not-found-error'
+
+export const Route = createRootRouteWithContext<{
+  queryClient: QueryClient
+}>()({
+  component: () => {
+    return (
+      <>
+        <Outlet />
+        <Toaster />
+        {import.meta.env.MODE === 'development' && (
+          <>
+            <ReactQueryDevtools buttonPosition='bottom-left' />
+            <TanStackRouterDevtools position='bottom-right' />
+          </>
+        )}
+      </>
+    )
+  },
+  notFoundComponent: NotFoundError,
+  errorComponent: GeneralError,
+})