Add initial project files

apps/backend/app/exceptions/api_exception.ts

@@ -0,0 +1,8 @@
+import { Exception } from '@adonisjs/core/exceptions'
+import type { HttpContext } from '@adonisjs/core/http'
+
+export default class ApiException extends Exception {
+  async handle(error: this, ctx: HttpContext) {
+    ctx.response.status(error.status).send({ message: error.message, code: error.code })
+  }
+}