feat: add onboarding with oldmarr import (#1606)

apps/nextjs/src/app/[locale]/init/_steps/back.tsx

@@ -0,0 +1,23 @@
+"use client";
+
+import { Button } from "@mantine/core";
+
+import { clientApi } from "@homarr/api/client";
+import { revalidatePathActionAsync } from "@homarr/common/client";
+import { useI18n } from "@homarr/translation/client";
+
+export const BackToStart = () => {
+  const t = useI18n();
+  const { mutateAsync, isPending } = clientApi.onboard.previousStep.useMutation();
+
+  const handleBackToStartAsync = async () => {
+    await mutateAsync();
+    await revalidatePathActionAsync("/init");
+  };
+
+  return (
+    <Button loading={isPending} variant="subtle" color="gray" fullWidth onClick={handleBackToStartAsync}>
+      {t("init.backToStart")}
+    </Button>
+  );
+};