feat: add onboarding with oldmarr import (#1606)

packages/old-import/src/prepare/prepare-single.ts

@@ -0,0 +1,21 @@
+import type { OldmarrConfig } from "@homarr/old-schema";
+
+import type { OldmarrImportConfiguration } from "../settings";
+import { prepareApps } from "./prepare-apps";
+
+export const prepareSingleImport = (config: OldmarrConfig, settings: OldmarrImportConfiguration) => {
+  const validAnalyseConfigs = [{ name: settings.name, config, isError: false }];
+
+  return {
+    preparedApps: prepareApps(validAnalyseConfigs),
+    preparedBoards: settings.onlyImportApps
+      ? []
+      : [
+          {
+            name: settings.name,
+            size: settings.screenSize,
+            config,
+          },
+        ],
+  };
+};