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/mkdirp-classic/README.md

@@ -0,0 +1,18 @@
+# mkdirp-classic
+
+Just a non-deprecated mirror of [mkdirp 0.5.2](https://github.com/substack/node-mkdirp/tree/0.5.1)
+for use in modules where we depend on the non promise interface.
+
+```
+npm install mkdirp-classic
+```
+
+## Usage
+
+``` js
+// See the above link
+```
+
+## License
+
+MIT