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/@aws-sdk/middleware-flexible-checksums/dist-es/stringHasher.js

@@ -0,0 +1,6 @@
+import { toUint8Array } from "@smithy/util-utf8";
+export const stringHasher = (checksumAlgorithmFn, body) => {
+    const hash = new checksumAlgorithmFn();
+    hash.update(toUint8Array(body || ""));
+    return hash.digest();
+};