fix: 修复配额说明重复和undefined问题

- 在editStorageForm中初始化oss_storage_quota_value和oss_quota_unit
- 删除重复的旧配额说明块，保留新的当前配额设置显示

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/node_modules/math-intrinsics/isNaN.js

@@ -0,0 +1,6 @@
+'use strict';
+
+/** @type {import('./isNaN')} */
+module.exports = Number.isNaN || function isNaN(a) {
+	return a !== a;
+};