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/utils-merge/index.js

@@ -0,0 +1,23 @@
+/**
+ * Merge object b with object a.
+ *
+ *     var a = { foo: 'bar' }
+ *       , b = { bar: 'baz' };
+ *
+ *     merge(a, b);
+ *     // => { foo: 'bar', bar: 'baz' }
+ *
+ * @param {Object} a
+ * @param {Object} b
+ * @return {Object}
+ * @api public
+ */
+
+exports = module.exports = function(a, b){
+  if (a && b) {
+    for (var key in b) {
+      a[key] = b[key];
+    }
+  }
+  return a;
+};