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/jws/lib/tostring.js

@@ -0,0 +1,10 @@
+/*global module*/
+var Buffer = require('buffer').Buffer;
+
+module.exports = function toString(obj) {
+  if (typeof obj === 'string')
+    return obj;
+  if (typeof obj === 'number' || Buffer.isBuffer(obj))
+    return obj.toString();
+  return JSON.stringify(obj);
+};