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/multer/lib/file-appender.js

@@ -0,0 +1,67 @@
+var objectAssign = require('object-assign')
+
+function arrayRemove (arr, item) {
+  var idx = arr.indexOf(item)
+  if (~idx) arr.splice(idx, 1)
+}
+
+function FileAppender (strategy, req) {
+  this.strategy = strategy
+  this.req = req
+
+  switch (strategy) {
+    case 'NONE': break
+    case 'VALUE': break
+    case 'ARRAY': req.files = []; break
+    case 'OBJECT': req.files = Object.create(null); break
+    default: throw new Error('Unknown file strategy: ' + strategy)
+  }
+}
+
+FileAppender.prototype.insertPlaceholder = function (file) {
+  var placeholder = {
+    fieldname: file.fieldname
+  }
+
+  switch (this.strategy) {
+    case 'NONE': break
+    case 'VALUE': break
+    case 'ARRAY': this.req.files.push(placeholder); break
+    case 'OBJECT':
+      if (this.req.files[file.fieldname]) {
+        this.req.files[file.fieldname].push(placeholder)
+      } else {
+        this.req.files[file.fieldname] = [placeholder]
+      }
+      break
+  }
+
+  return placeholder
+}
+
+FileAppender.prototype.removePlaceholder = function (placeholder) {
+  switch (this.strategy) {
+    case 'NONE': break
+    case 'VALUE': break
+    case 'ARRAY': arrayRemove(this.req.files, placeholder); break
+    case 'OBJECT':
+      if (this.req.files[placeholder.fieldname].length === 1) {
+        delete this.req.files[placeholder.fieldname]
+      } else {
+        arrayRemove(this.req.files[placeholder.fieldname], placeholder)
+      }
+      break
+  }
+}
+
+FileAppender.prototype.replacePlaceholder = function (placeholder, file) {
+  if (this.strategy === 'VALUE') {
+    this.req.file = file
+    return
+  }
+
+  delete placeholder.fieldname
+  objectAssign(placeholder, file)
+}
+
+module.exports = FileAppender