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/text-decoder/lib/browser-decoder.js

@@ -0,0 +1,17 @@
+module.exports = class BrowserDecoder {
+  constructor (encoding) {
+    this.decoder = new TextDecoder(encoding === 'utf16le' ? 'utf16-le' : encoding)
+  }
+
+  get remaining () {
+    return -1
+  }
+
+  decode (data) {
+    return this.decoder.decode(data, { stream: true })
+  }
+
+  flush () {
+    return this.decoder.decode(new Uint8Array(0))
+  }
+}