fix(@vben/web-antd): 移除文件配置自定义域名的必填校验

自定义域名为可选项，移除多余的 required 规则。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web-antd/src/views/infra/fileConfig/data.ts

@@ -249,7 +249,6 @@ export function useFormSchema(): VbenFormSchema[] {
       componentProps: {
         placeholder: '请输入自定义域名',
       },
-      rules: 'required',
       dependencies: {
         triggerFields: ['storage'],
         show: (formValues) => !!formValues.storage,