docs: add Resend DNS-only proxy warning to prevent #515-style verification failures (#1062)

docs: add Resend DNS-only proxy warning to send-mail config

Resend domain verification CNAME records must use DNS-only (gray
cloud) on Cloudflare. Proxied (orange cloud) records prevent
verification, and a single failed attempt can take hours before
retry. This is a recurring issue (#515) that the Resend setup
docs did not warn about.

Co-authored-by: CommandCodeBot <noreply@commandcode.ai>

vitepress-docs/docs/en/guide/config-send-mail.md

@@ -48,6 +48,12 @@ No additional env var is required.
 
 Register at `https://resend.com/domains` and add DNS records according to the instructions.
 
+> [!WARNING] DNS record proxy status on Cloudflare
+> Resend domain verification CNAME records **must be set to DNS-only** (gray cloud) in
+> the Cloudflare DNS dashboard. Proxied (orange cloud) records will prevent Resend from
+> completing verification, and a single failed attempt can take several hours before
+> Retry becomes available. See [#515](https://github.com/dreamhunter2333/cloudflare_temp_email/issues/515).
+
 Create an `api key` on the `API KEYS` page.
 
 Then execute the following command to add `RESEND_TOKEN` to secrets:

vitepress-docs/docs/zh/guide/config-send-mail.md

@@ -48,6 +48,12 @@ send_email = [
 
 注册 `https://resend.com/domains` 根据提示添加 DNS 记录,
 
+> [!WARNING] Cloudflare 上 DNS 记录的代理状态
+> Resend 域名验证的 CNAME 记录**必须设置为 仅 DNS**（灰云），在
+> Cloudflare DNS 控制面板中代理（橙云）记录会阻止 Resend
+> 完成验证，且一次失败的尝试可能需要数小时才能重试。
+> 参见 [#515](https://github.com/dreamhunter2333/cloudflare_temp_email/issues/515)。
+
 `API KEYS` 页面创建 `api key`
 
 然后执行下面的命令，将 `RESEND_TOKEN` 添加到 secrets 中