Update formatting rules to enforce consistent tab-based indentation across the backend

backend/src/app.service.ts

@@ -1,8 +1,8 @@
-import { Injectable } from '@nestjs/common';
+import { Injectable } from "@nestjs/common";
 
 @Injectable()
 export class AppService {
-  getHello(): string {
-    return 'Hello World!';
-  }
+	getHello(): string {
+		return "Hello World!";
+	}
 }