impl simple backend

backend/src/controller/app.controller.ts

@@ -0,0 +1,12 @@
+import { Controller, Get } from "@nestjs/common";
+import { AppService } from "../service/app.service";
+
+@Controller()
+export class AppController {
+  constructor(private readonly appService: AppService) {}
+
+  @Get()
+  getHello(): string {
+    return this.appService.getHello();
+  }
+}