fix: deleted root Hello world example

backend/src/app.controller.ts

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

backend/src/app.service.ts

 import { Injectable } from '@nestjs/common';
 
 @Injectable()
-export class AppService {
-  getHello(): string {
-    return 'Hello World!';
-  }
-}
+export class AppService {}