refactor: Projektstruktur in app/ und backend/ aufgeteilt

backend/vite.config.ts

@@ -0,0 +1,9 @@
+import { UserConfigFn } from 'vite';
+import { overrideVaadinConfig } from './vite.generated';
+
+const customConfig: UserConfigFn = (env) => ({
+  // Here you can add custom Vite parameters
+  // https://vitejs.dev/config/
+});
+
+export default overrideVaadinConfig(customConfig);