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/append-field/test/forms.js

@@ -0,0 +1,19 @@
+/* eslint-env mocha */
+
+var assert = require('assert')
+var appendField = require('../')
+var testData = require('testdata-w3c-json-form')
+
+describe('Append Field', function () {
+  for (var test of testData) {
+    it('handles ' + test.name, function () {
+      var store = Object.create(null)
+
+      for (var field of test.fields) {
+        appendField(store, field.key, field.value)
+      }
+
+      assert.deepEqual(store, test.expected)
+    })
+  }
+})