fix(backend): clone schema before converting to OAS schema to avoid mutation (#15294)

* fix(backend): clone schema before converting to OAS schema to avoid mutation

* Update CHANGELOG.md

* fix: use deepClone

packages/backend/src/server/api/openapi/schemas.ts

@@ -3,13 +3,15 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+import { deepClone } from '@/misc/clone.js';
 import type { Schema } from '@/misc/json-schema.js';
 import { refs } from '@/misc/json-schema.js';
 
 export function convertSchemaToOpenApiSchema(schema: Schema, type: 'param' | 'res', includeSelfRef: boolean): any {
 	// optional, nullable, refはスキーマ定義に含まれないので分離しておく
 	// eslint-disable-next-line @typescript-eslint/no-unused-vars
-	const { optional, nullable, ref, selfRef, ...res }: any = schema;
+	const { optional, nullable, ref, selfRef, ..._res }: any = schema;
+	const res = deepClone(_res);
 
 	if (schema.type === 'object' && schema.properties) {
 		if (type === 'res') {