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/@smithy/util-base64/dist-es/fromBase64.js

@@ -0,0 +1,12 @@
+import { fromString } from "@smithy/util-buffer-from";
+const BASE64_REGEX = /^[A-Za-z0-9+/]*={0,2}$/;
+export const fromBase64 = (input) => {
+    if ((input.length * 3) % 4 !== 0) {
+        throw new TypeError(`Incorrect padding on base64 string.`);
+    }
+    if (!BASE64_REGEX.exec(input)) {
+        throw new TypeError(`Invalid base64 string.`);
+    }
+    const buffer = fromString(input, "base64");
+    return new Uint8Array(buffer.buffer, buffer.byteOffset, buffer.byteLength);
+};